In order to study the changes of gut hormones and gastric motility in gastric cancer patients, the concentrations of motilin (MOT) in plasma and duodenal juice were measured by RIA, and the intragastric pressure of the pylorus, the body and the fundus of the stomach of 33 gastric cancer patients were measured using a WYY-B Manometer (produced by Areomedicine Research Institute, Beijing, China). The results showed that MOT concentrations of both plasma and duodenal juice were significantly higher than that of healthy controls (P < 0.05-0.01), and that of duodenal juice was about 3 times higher than in healthy controls. The basic intragastric pressure and the wave pressure of the pylorus, body and fundus of the patients were significantly lower than that of control subjects (P < 0.01). Almost all the intragastric wave pressure of the patients were of inhibition type, especially that of at or near the cancer masses. Our results indicate that there were marked drop in the stomach tension and motility in gastric cancer patient, while the increased MOT concentrations of plasma and duodenal juice were due to the pathological compensation.