Fallout Wiki
Fallout Wiki

Initial trial runs resulted in significant abdominal deformation, displacement of internal organs and massive internal hemorrhaging.

Subsequent formulas reduced the debilitating physical effects, but marked reduction in cognitive function continued to be a problem.

The development team suggested abandoning this particular serum, but it was decided the potential advantage to military personnel in the field was too great to pass up.
The Whitespring bunker terminal entries

Marsupial is a mutation in Fallout 76.


Positive effects
Carry Weight +20, improved jump height.
Negative effects
-4 Intelligence.


  • The reduction in Intelligence does not affect perk card slots for the player character but does affect Intelligence when calculated for everything else, such as checks in conversation or the xp bonus calculations.
  • The negative effects can be temporarily suppressed by consuming another serum, or reduced down to a max of -1 with Class Freak level 3.