Seven patients were studied to evaluate the effect of trimebutine maleate on diabetic diarrhea. All patients had severe autonomic neuropathy. Improvement was assessed on the basis of subjective symptoms (diarrhea score) after oral administration of trimebutine maleate (300 mg/day). Within two days, severe diarrhea was markedly reduced. No side effects were observed in any of the patients. The results of this study suggest that trimebutine maleate may serve as a useful drug in improving the symptom of diabetic diarrhea.