After overnight fasting test subjects exposed to head-down tilt showed an increase in the amplitude of stomach biopotentials, thus suggesting an increase in its contractile force. A provocative food test demonstrated an increase in the excitability of the stomach neuromuscular apparatus due to 30-day head-down tilt, which included an increment of contraction amplitudes and rates. The amplitude increase occurred both before and after food intake. However, an analysis of the wave amplitude composition showed a shift to the right which was most distinct in the fasting state. This indicated that the stomach motor activity in the digestive period showed greater resistance to head-down tilt. An increase in the asymmetry coefficient before and after food intake proportional to the head-down tilt duration suggests that the stomach evacuatory activity was inhibited.