The duration of the disruption of the interdigestive migrating myoelectric complex (MMC) by various test meals in dogs was correlated with changes in serum gastrin and insulin levels. The test meals consisted of milk protein, sucrose, arachis oil and medium chain triglycerides (MCT). Intravenous infusions of glucose 20% were also used. Electrical activity of the small intestine was registered by means of electrodes implanted over the entire length of the gut. Hormones were assayed by radioimmunoassay techniques. The insulin level rose significantly after both the glucose infusion and the sucrose meal. The rise was small after the milk protein meal and nothing after arachis oil and MCT. Gastrin level was not changed by arachis oil or MCT and rose slightly after sucrose and milk protein. The MMC was not disrupted by glucose infusions, but was disrupted for 5--7 h by archis oil and for 6--12 h by MCT. We conclude that in dogs neither gastrin nor insulin have an important role in the mechanism of disruption of the MMC after feeding.