Cryptosporidiosis commonly causes severe diarrhea in immunosuppressed patients. There currently are no antiparasitic drugs consistently effective for this infection. This case describes a 26-year-old hemophiliac patient with acquired immunodeficiency syndrome and cryptosporidiosis whose diarrhea improved with continuous intravenous administration of a long-acting somatostatin analog, octreotide. Somatostatin has a variety of inhibitory effects on gastrointestinal hormones as well as a possible nonspecific effect on gastrointestinal mucosal fluid and electrolyte secretion. The somatostatin analog should be considered for patients with secretory diarrhea refractory to other forms of therapy.