Six male volunteers for dry immersion (DI) simulating microgravity effects in the human body were subjects in the study on the evacuation function of the gastrointestinal tract (GIT). The investigation was aimed to evaluate liquid food evacuation from the stomach (the 13C-acetate test) and time of chymus orocecal transit (the H2-inulin test). The 13C-acetate test did not reveal changes in stomach evacuation activity after 4 days in DI. The H2-inulin test demonstrated shortening of the chymus’s transit along the small intestine and extension of chymus passage from the oleum to cecum. The subsequent reduction of inulin metabolism in the large intestine suggested inhibited passage of these GIT segments. The results showed that the stability of liquid evacuation from the stomach and acceleration of the chymus’s transit along the small intestine hinder evacuation of the large intestine content, which is the primary cause of the inhibition of the GIT evacuation activity during DI.