A diabetic patient was treated with a somatostatin analogue, SMS 201-995, to control chronic diarrhea and orthostatic hypotension. The patient was injected with 50 micrograms, 100 micrograms, and 150 micrograms of SMS 201-995 subcutaneously twice daily for three days at each dose. Stool weight decreased from a basal mean value of 906 g per 24 hours to 628 g, 445 g, and 408 g per 24 hours, respectively. Diarrhea remained suppressed for 18 months when the patient was last seen. When SMS 201-995 was then given at 5 micrograms to 10 micrograms per hour by continuous subcutaneous infusion, stool weight decreased to a mean of 321 g per 24 hours. Basal blood pressure, which averaged 99/71 mm Hg, rose to 133/91 mm Hg five minutes after 75 micrograms of SMS 201-995 was injected subcutaneously; it remained elevated for six hours after injection. Serum motilin levels decreased significantly from 126 pg/ml before injection of SMS 201-995 to 52 pg/ml after injection. Serum norepinephrine levels rose from 50 pg/ml supine (normal range, 150 to 550 pg/ml) and 52 pg/ml erect before injection of SMS 201-995 to 72 pg/ml supine and 110 pg/ml erect after injection. SMS 201-995 may raise blood pressure, in part by increasing the release of circulating norepinephrine.