Shifts of body fluids from the legs and torso toward the head may contribute to the motion sickness experienced by astronauts and cosmonauts. The shifts in body fluids observed during 0g exposure were simulated by elevating guinea pig and monkey torsos and hindquarters. CSF pressure was recorded from a transducer located in a brain ventricle; labyrinth fluid pressure was recorded from a pipette cemented in a hole in a semicircular canal. An anticipated divergence in CSF pressure and labyrinth fluid pressure during torso elevation was not observed. A fluid shift mechanism of 0g-induced motion sickness was not found. A more complete test of the fluid shift mechanism may be obtained if endolymph and perilymph pressure changes were determined separately.