A method of recording gastric myoelectric activity with a peroral suction electrode was evaluated, and the recording was compared with that obtained by implanted electrodes on the serosal surface of the stomach of laparotomized humans. In a group of patients with unexplained nausea, epigastric bloating, and vomiting, abnormal antral myoelectric activities were found by a peroral electrode, in contrast to a regular pacesetter potential (frequency: 3-4/min) in control subjects. These abnormalities were confirmed by the recordings from the implanted electrodes in the same subjects. The study indicates that peroral recording of gastric myoelectric activity is a useful diagnostic method for the detection of gastric myoelectric activity abnormalities in humans.