AIM: To investigate the effects of psychological stress on small intestinal motility and expression of cholecystokinin(CCK) and vasoactive intestinal polypeptide (VIP) in plasma and small intestine, and to explore the relationship between small intestinal motor disorders and gastrointestinal hormones under psychological stress.METHODS: Thirty-six mice were randomly divided into psychological stress group and control group. A mouse model with psychological stress was established by housing the mice with a hungry cat in separate layers of a two-layer cage. A semi-solid colored marker (carbon-ink) was used for monitoring small intestinal transit. CCK and VIP levels in plasma and small intestine in mice were measured by radioimmunoassay (RIA).RFSULTS: Small intestinal transit was inhibited (52.18±19.15%vs 70.19±17.79%, P＜0.01) in mice after psychological stress, compared to the controls. Small intestinal CCK levels in psychological stress mice were significantly lower than those in the control group (0.75±0.53 μg/g vs 1.98±1.17 μg/g,P＜0.01), whereas plasma CCK concentrations were not different between the groups. VIP levels in small intestine were significantly higher in psychological stress mice than those in the control group (8.45±1.09 μg/g vs 7.03±2.36 μg/g,P＜0.01), while there was no significant difference in plasma VTP levels between the two groups.CONCLUSION: Psychological stress inhibits the small intestinal transit, probably by down-regulating CCK and up-regulating VIP expression in small intestine.