The effects of juice from Morinda citrifolia (noni) on gastric emptying, gastrointestinal transit, and plasma level of cholecystokinin (CCK) in rats were studied. Male rats were given noni by gavage at levels of 0.25, 1, or 4 ml/kg once per day for one or 7 days. The rats in the control group were given water, while the rats in the experimental group were fasted overnight before measurement of gastrointestinal motility. Gastrointestinal motility was assessed in rats 15 min after intragastric instillation of a test meal containing charcoal (10%) and Na251CrO4 (0.5 microCi/ml). Gastric emptying was determined by measuring the amount of radiolabeled chromium contained in the small intestine as a percentage of the initial amount received. Then, gastrointestinal transit was evaluated by calculating the geometric center of distribution of the radiolabeled marker. Finally, blood samples were collected for measurement of CCK by radioimmunoassay. The administration of noni at 0.25 ml/kg, but not at 1 ml/kg and 4 ml/kg, for 1 day significantly inhibited gastric emptying. In contrast, gastric emptying was significantly inhibited by oral noni (0.25, 1, or 4 ml/kg) for 7 days. Intraperitoneal injection of lorglumide (5 or 10 mg/kg), a selective CCK1 receptor antagonist, effectively attenuated the noni-induced inhibition of gastric emptying. The intestinal transit and body weight, food intake, water intake, urine volume as well as feces weight were not altered by the administration of noni either acutely or chronically, but the administration of oral noni (1 ml/kg) for 7 days increased the level of plasma CCK in male rats. These results suggest that oral noni inhibits gastric emptying in male rats via a mechanism involving stimulation of CCK secretion and CCK1 receptor activation.