The gastric secretion was systematically examined in 58 patients during the first days after operations on organs of the abdominal cavity, 23 of them having it considerably increased. In three of these patients the operation was followed by gastric bleeding from acute ulcers. Higher gastric secretion was most frequently observed in patients with mechanical jaundice, purulent peritonitis and intestinal obstruction. Changes in the gastric secretion depend on the composition and volume of infusion therapy.