The effect of intravenous bolus injection of the somatostatin analogue SMS 201-995 on mucosal and submucosal blood flow was studied with the local 133Xe clearance technique in eight subjects. Mucosal and submucosal blood flow decreased by 33% after injection of SMS 201-995. These observations suggest that SMS 201-995, like somatostatin, inhibits splanchnic blood flow.