Somatostatin has been shown to inhibit intestinal secretion induced by a variety of secretagogues. The ability of somatostatin to reduce stool output in patients with cholera was therefore investigated in a double-blind randomized controlled trial. Twenty-two patients with severe purging due to infection with Vibrio cholerae (less than or equal to 12.5 ml/kg X h) received either somatostatin at a dose of 250 micrograms/h in saline (n = 12) or placebo (n = 10). The study drug was given for 12 h followed by a control period of the same duration. No difference in stool output was apparent between somatostatin- and placebo-treated groups. No side effects of somatostatin were observed. It is concluded that somatostatin is ineffective as an antidiarrheal agent in Asiatic cholera in humans.