Effects of vagotomy on gastric motor activity were studied on 39 patients after vagotomy for gastric or duodenal ulcer by fluoroscopic examination and by monitoring of intragastric pressure using a balloon introduced into the stomach. These patients were divided into three groups according to types of vagotomy; selective proximal vagotomy (SPV), selective vagotomy (SV) and atypical selective proximal vagotomy. In atypical SPV, dorsal antral branches of vagal gastric nerves were sacrificed in addition to conventional SPV because of local conditions around the ulcer. In patients after SPV or atypical SPV, no gastric stasis was observed on fluoroscopic examination. However, marked gastric stasis with delayed emptying was a constant finding in patients after SV, especially at the early postoperative period. In recording of intragastric pressure, basic peristaltic waves of a 20-second rhythm were observed following inflation of the balloon in all patients after any type of vagotomy. In addition, an alternation of active and resting periods of motor activity and confluence of large waves at the end of active period were observed as characteristoc findings in patients after both SPV and atypical SPV. The large waves were considered to coincide with active propulsive movements seen on fluoroscopy in these patients. The results in this study confirmed that good gastric motility could be preserved in patients after SPV and even after atypical SPV.