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The Mesmetron is a unique weapon in Fallout 3.


Developed by Implied Hypnotics, Inc. before the War, the Mesmetron is an experimental "non-lethal subjugation device" provided to the United States military for them to assist in experimental trials.[1] It operates by sending a series of waves that the brain attempts to decode, but because the synapses are being overwhelmed by the neural static, the brain becomes confused and switches off important higher-level mental functions and voluntary motor control,[1] leaving the target extremely susceptible to suggestion.[2] Still in its testing phase, the weapon was found to have the potential to trigger two undesirable side-effects: extremely increased aggression or a "resonant brain wave feedback loop" which resulted in spontaneous cranial eruption.[1] Despite the prototypical nature of the device, several were attached to robobrains to add in the interrogation processes. (Officially noting the 10-15% casualties due to spontaneous cranial eruption.)[3]

The model given to the Lone Wanderer in Paradise Falls was scavenged from an old military base by Grouse.[4][5] The Mesmetron is invaluable to slavers, making it a cakewalk to capture slaves, which are left senseless by the Mesmetron waves.[6][7][8] However, caution must be exercised when using the Mesmetron around already collared slaves, because the waves interfere with the collar's radio signals and cause it to unintentionally detonate.[9]


When used on the specified quest non-player characters, it puts them into a hypnotic stupor, allowing the player character to rob and enslave them (by putting a slave collar on them) and send them to Paradise Falls. It also appears to work on many other non-player characters (aside from quest related ones), but can simply send them into a berserk frenzy in which they turn hostile to the Lone Wanderer and every other non-player character in the area. Occasionally, victims will run several steps before their heads explode.


The Mesmetron can fire a total of 2500 waves, or 500 full cells, from full condition before breaking.

Using the Mesmetron[]

As previously mentioned, using the Mesmetron on a non-player character can have three different outcomes. These effects vary and are generally unreliable, so it is advised to save before using this weapon on anyone important. Because using the Mesmetron is considered assault, it is advised to "mezz" someone while undetected. Be aware that mezzing anyone who is already wearing a slave collar will cause the collar to malfunction and explode, killing the victim. Hostile non-player characters who were mezzed can also be turned friendly by being freed by the player character (high Science skill required). An analysis of the Mesmetron's effects:



A female raider stunned by the Mesmetron

With a 50% probability, this effect stuns the target for a few seconds, during which time the victim will stand with their head swaying from side to side and it is possible to engage them in conversation. Some characters cannot be stunned, in which case the probability of the Frenzy effect is raised to 80%.

While in conversation, there are three dialogue options:

  • The first will open the character's inventory (by either telling them it's a magic trick, that there is a thief on the loose, that the player character thinks they stole something from them, or by just telling them to give their things) including currently equipped items, allowing the player character to give or take any item as desired.
  • The second puts a slave collar on the character, giving negative Karma.
  • The third simply tells the victim to "walk it off"; this will exit the conversation and make the character resume what they were doing (assuming no onlookers turned hostile).

The second set of dialogue options is unlocked by slipping a collar onto the victim: The first is the "cruel" way to tell the victim that they are now a slave ("...your head will explode!"), the second option allows access to the slave's inventory, and the third option is a slightly friendlier way to inform the victim of their "new occupation" ("...nothing personal").

If the character is not spoken to before the stun effect wears off, they will turn hostile towards anyone they can see, that includes the player character.


For a 30% chance to occur, this second effect causes the victim to go into a state of frenzy, attacking anyone nearby (most likely the player character), and causing all other characters to turn on them. The onlookers may also turn hostile to the PC if caught stunning the victim. This method can also be a reliable way to get rid of victims without attacking them or getting negative Karma. This is dangerous, however, especially if one of the enemies has any high-damaging weapons.

Spontaneous cranial eruption[]

With a 20% probability, this final effect of the Mesmetron may not be the most useful, but is definitely the most spectacular. When victims are affected by the Mesmetron in this way, they will turn hostile (and either run, stand still, or attack) for just a moment before their heads literally explode. This effect will instantly give negative Karma (if the victim was good/neutral) and turn any nearby non-player characters hostile to the player character.



Weapon name (current weapon is highlighted)- Weapon name (melee or unarmed)Attacks in V.A.T.S.- Attacks in V.A.T.S.
Weapon name (current weapon is highlighted)- Weapon name (gun, energy or explosive)Action point cost- Action point cost
Damage per attack (damage per projectile)- Damage per attack (damage per projectile)Damage per action point- Damage per action point
Damage per second- Damage per secondWeapon spread- Weapon spread
Area of effect damage- Area of effect damageMagazine capacity (shots per reload)- Magazine capacity (shots per reload)
Effect damage & duration- Effect damage & durationDurability (number of attacks before breaking)- Durability (number of attacks before breaking)
Bonus effects- Bonus effectsWeight- Weight
Attacks per second- Attacks per secondValue in caps- Value in caps
Critical chance % multiplier- Critical chance % multiplierValue to weight ratio- Value to weight ratio
Critical damage- Critical damageSkill required- Skill required
Critical effect damage & duration- Critical effect damage & durationStrength required- Strength required
With all mods attached- With all mods attached
Weapon name (current weapon is highlighted)Damage per attack (damage per projectile)Damage per secondBonus effectsAttacks per secondCritical Chance % multiplierCritical damageAction Point costDamage per action pointWeapon spreadMagazine capacity (shots per reload)Durability (number of attacks before breaking)WeightValue in capsValue to weight ratio
Mesmetron 1
1Chance to mesmerize(50%),
frenzy(30%), or head explode (20%)
Microwave emitter Point Lookout (add-on)60
62.1Ignores DR1.03x21003020.25375850062.5


The Mesmetron is given to the Lone Wanderer by Grouse, the Paradise Falls entrance guard, upon starting the quest Strictly Business.

If deciding not to take the quest, the Mesmetron can be obtained by killing Grouse and looting his corpse. It cannot be stolen from him, meaning he needs to be dead to get it. If this is done, it's no longer possible to purchase any Mesmetron power cells nor slave collars from him, thus one can't enslave non-player characters. The Mesmetron can still be exploited to frenzy or stun and rob non-player characters, however.

Related quests[]


  • Robobrains have this weapon built-in, though it only causes damage, not frenzy or hypnosis.
  • Enslavable targets are based on a faction list of 672 members, filled mostly with generic non-player characters. There's a shorter faction list of non-player characters who can always be mezzed, and this initially includes the four objectives of the Strictly Business quest and one generic leveled slave. Essential non-player characters may be immune.
    • A (possibly incomplete) list of enslavable non-player characters is located on the Strictly Profitable page.
    • After a non-player character is successfully mezzed they are added to a faction list that can never be mezzed.
  • A slave collar is required to enslave someone. Only one collar can be carried and therefore only one person may be enslaved at a time.
    • It appears that unarmed (or disarmed) non-player characters are more likely to be enslaved by the Mesmetron. Attacking a non-player character's weapon or arms and then switching to the Mesmetron may be an effective technique.
    • Using the Mesmetron in V.A.T.S. can result in the Mysterious Stranger appearing if having the perk. The Mysterious Stranger will not fire on the target if they were successfully stunned, though V.A.T.S. will remain active for the usual period of time.
    • Non-player characters can be enslaved, even if all of the slavers in Paradise Falls are dead.
  • Any enslaved raiders will almost never get to Paradise Falls alive, even if fast traveling there.
  • For each non-player character successfully enslaved:
    • Grouse pays 250 bottle caps per slave.
    • Enslaving anyone deducts 100 Karma, regardless of how evil they are. As Three Dog exclaims, "the selling of live human beings is completely fucked up!"
    • A good way to offset the Karma loss (if wishing to be good or neutral), is to donate 100 caps to either Confessor Cromwell of Megaton or Father Clifford of Rivet City.
    • The game will keep track of how many characters were "mezzed." This information can be accessed on the Pip-Boy.
  • Generic non-player characters (such as raiders) who are enslaved and successfully sent to Paradise Falls will not respawn.
    • One must consider if they want to interact with the character again before enslaving them.
    • Significant use of the Mesmetron in a specific area can permanently clear that area of human enemies.
    • Additionally, enslaving a generic, hostile non-player character and then subsequently removing the slave collar will cause the non-player character to turn friendly to the Lone Wanderer and companions (other alliances/hostilities, e.g. Brotherhood of Steel vs. Enclave, are not affected). This change persists, even if the non-player character is killed and later respawns. Affected non-player characters will attack their usual allies (e.g. other Enclave members) if those allies attack the player character.
  • From time to time, a mesmerized and collared target won't make it to Paradise Falls. This causes the collar to be lost and as no slave was turned in, the collar must be re-purchased from the slavers. To ensure success, fast-travel to Paradise Falls if possible. (see bugs for more)
  • Followers may briefly attempt to attack a non-hostile non-player character once that NPC is stunned; this is because the non-player character will temporarily turn hostile to the Lone Wanderer before the stun effect kicks in.
  • "Mezzing" anyone in the Citadel Laboratory will automatically frenzy them (after the quest "The American Dream"). Witnesses will not turn hostile to the player.
  • If the Mesmetron is used on an unfreed captive and they are then freed, it is then impossible to interact with them again, except to mezz or kill them.
  • It is to be noticed that in third person, the Mesmetron has no trigger.
  • The Mesmetron's light is visible when the stealth field of a Stealth Boy or the Chinese stealth armor is in use. It will not be on, however, if it is equipped (not unholstered) after the stealth field kicks in. (The light is always on in 1st person. In 3rd person, it can vary depending on how the Lone Wanderer equips it.)
  • There is a mention of the Mesmetron in Fallout 4 on a terminal at the second floor of the HalluciGen, Inc. building, indicating that the lead engineer for its development also worked for HalluciGen.[10]
  • Robobrains in the RobCo Sales & Service Center are equipped with Mesmetrons.[11]


  • PCPC Freshly enslaved non-player characters will often be reported by Grouse to have died once the Lone Wanderer arrives at Paradise Falls. This is caused by a condition in the Mesmetron effect script which automatically moves the slave to Paradise Falls—indirectly marking them as dead in the process—once the non-player character is no longer being actively rendered. Aside from leaving the non-player character's immediate vicinity, numerous actions have a random chance to cause a non-player character to stop being rendered, including accessing the Pip-Boy, facing away from the non-player character for a certain period, or even accessing the game menu. [verified]
  • PCPC Playstation 3Playstation 3Playstation 3 Xbox 360Xbox 360 "Mezzing" characters who are seated, leaning on a wall or lying down may cause them to spin rapidly in place before their heads explode. [verified]

See also[]

  • Slave collar - Used to enslave non-player characters once they are mezzed.


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  1. 1.0 1.1 1.2 Mesmetron manual - summary page
  2. The Lone Wanderer: "How do I get it on a slave?"
    Grouse: "Look. I gave you that Mesmetron thing. Should be a piece of cake. Hell, if you hit them with that thing and it works, I bet they'd put it on themselves if you asked."
    (Grouse's dialogue)
  3. RobCo Sales & Service Center terminal entries; Security Office Terminal, (045): Class-V Counter-Espionage Procedure
  4. The Lone Wanderer: "Where did you find it?"
    Grouse: "Found it in a box locked up in some old military base. I've been meaning to test it out, but Eulogy keeps me so busy, I don't got time. Besides, glancing at that manual, looks like it's a bit... unstable. Thanks for testing it out for me!"
    (Grouse's dialogue)
  5. The Lone Wanderer: "How's the Mesmetron work?"
    Grouse: "How the hell should I know? I found it in some old military base. It's a gun, ain't it? Point it at someone and pull the trigger. Did you even look at the manual? You like wasting my time, don't you?"
    (Grouse's dialogue)
  6. The Lone Wanderer: "What's this mutually beneficial offer you mentioned?"
    Grouse: "I got this Mesmetron thing. It's some kind of stun gun. I'd like you to test it out for me. Should make getting slaves easier. You take this Mezzer. Shoot it at some poor schmuck. While he's in la-la-land, you slip one of these collars over his head. Be careful with that collar. It'll explode if you tinker with it. Tell the slave to boot it over here pronto, or his head'll pop. Here's a list of special targets Eulogy wants enslaved. But feel free to put a collar on anyone you can. I'll pay you for each slave that arrives."
    (Grouse's dialogue)
  7. The Lone Wanderer: "I'll round up some slaves for you. But what's the catch?"
    Grouse: "I'm glad you asked! I got this Mesmetron thing. It's some kind of stun gun. I want you to test it out for me. A little research project. You take this Mezzer. Shoot it at some poor schmuck. While he's in la-la-land, you slip one of these collars over his head. Be careful with that collar. It'll explode if you tinker with it. Tell the slave to boot it over here pronto, or his head'll pop. You got all that? I hate repeating myself. That Mesmetron came with some kind of manual. I don't have time for that bullshit, so you better know how to read."
    (Grouse's dialogue)
  8. The Lone Wanderer: "I'll get your slaves."
    Grouse: "One more thing. I got this Mesmetron thing. It's some kind of stun gun. I want you to test it out for me. A little research project. You take this Mezzer. Shoot it at some poor schmuck. While he's in la-la-land, you slip one of these collars over his head. Be careful with that collar. It'll explode if you tinker with it. Tell the slave to boot it over here pronto, or his head'll pop. You got all that? I hate repeating myself. That Mesmetron came with some kind of manual. I don't have time for that bullshit, so you better know how to read."
    (Grouse's dialogue)
  9. Slave collar instructions
  10. HalluciGen, Inc. terminal entries; Development lab terminal
  11. RobCo Sales & Service Center terminal entries; Security office terminal, (045): Class-V Counter-Espionage Procedure