Classic diaphragmatic flutter, a rare disorder associated with dyspnoea, thoracic or abdominal wall pain, and epigastric pulsations, is caused by involuntary contractions of the diaphragm with a frequency of 0.5-8.0 Hz. We have seen three patients with diaphragmatic flutter of higher frequency not associated with respiratory disease. The patients presented with longstanding oesophageal belching, hiccups, and retching, respectively. The diagnosis was established by the presence on electromyography of the diaphragm and scalene and parasternal intercostal muscles of repetitive discharges of 9-15 Hz. Spirographic tracings, especially those of volume or flow vs time, showed similar high-frequency oscillations superimposed on tidal respiratory movements. Treatment with carbamazepine 200-400 mg three times daily led to disappearance or great improvement of flutter and clinical symptoms in all three patients. The phenomenon was not seen in other patients with chronic hiccups or oesophageal belching or in patients without these symptoms who had undergone electromyography or spirography for other reasons. Thus, high-frequency diaphragmatic flutter seems to be a new disease entity. The response to carbamazepine, which suggests that the flutter causes the symptoms, requires further study.