The effect of octreotide on sphincter of Oddi motility was investigated in six liver transplant patients, employing percutaneous (through the T-tube tract) manometry. Continuous and simultaneous sphincter of Oddi and duodenal motor activities were recorded before and for 60 min after the administration of octreotide (100 micrograms subcutaneously) and after the injection of cholecystokinin (0.02 microgram/kg intravenously). With octreotide, contraction frequency and basal pressure significantly increased (P < 0.05). This effect lasted more than 60 min, long after octreotide-induced duodenal migrating motor complex phase III activity had ceased. Sphincter of Oddi contraction amplitude and duration were unaffected by octreotide. Subsequent cholecystokinin administration transiently reduced sphincter of Oddi basal pressure and contraction frequency. We conclude that octreotide significantly increases sphincter of Oddi basal pressure and contraction frequency. This effect is distinct from octreotide induction of migrating motor complex phase III activity, persists for a prolonged period, and is inhibited by cholecystokinin.