Change in functional activity of digestive system in space flight usually is associated with phenomenon of hypokinesia which takes place in microgravity. However, it is marked that the reorganization of a gastrointestinal tract in space flight occurs on a background of the phenomenon of venous plethora in abdominal cavity, which can also result in changes of functional activity in organs of digestive system. Insignificant amount of studies of venous plethora in abdominal cavity carried out in conditions of space flight does not allow to create a complete picture of this phenomenon. Hemodynamical changes comparable to microgravity are well-simulated in conditions of a long-term antiorthostatic hypokinesia (AH)--bed-rest in a head-down tilt. The present research was performed with the aim to study venous plethora in abdominal cavity in conditions of long-term AH.