The synthetic disaccharide lactulose, consisting of fructose and galactose, after oral administration in an unchanged form reaches the lower part of the gastrointestinal tract, where under the action of normal flora it is broken down into short-chain fatty acids that stimulate colon motility. The effect of lactulose on gastrointestinal tract motility in the conditions of its long-term suppression by omeprazole has not been investigated. We studied the influence of lactulose on spontaneous and carbachol-stimulated gastric and colonic motility in rats treated with omeprazole for 28 days. The animals were divided into 3 groups. The first group of animals served as a control. The animals in the second group were administered omeprazole intraperitoneally at a dose of 14 mg/kg orally once a day for 28 days. The animals in the third group were simultaneously injected intraperitoneally with omeprazole and prebiotic lactulose at a dose of 0.2 g/kg orally once a day for 28 days. On the day after the last injections of drugs, we investigated the spontaneous and carbachol-stimulated contractions in the stomach and colon by the balloon graphic method. It was found that the frequency of spontaneous and stimulated contractions in the stomach and colon did not change significantly after 28 days of omeprazole treatment. The amplitude and index of spontaneous and carbachol-stimulated contractions in the stomach and colon were significantly weaker compared to the control. One day after the 28-day simultaneous administration of omeprazole and lactulose the amplitude and index of spontaneous and stimulated contractions in the stomach and colon increased compared with the group of rats treated with omeprazole alone. We concluded that the positive effect of lactulose on gastric and colon motility is a result of the prebiotic properties of lactulose which leads to the normalization of the microbiocenosis in the gastrointestinal tract and the elimination of the inflammatory process in it.