Nineteen consecutive patients with acute pancreatitis were sequentially allocated to treatment with high-dose octreotide (N = 9) or to act as controls (N = 10). All other aspects of treatment were similar and were according to a strict treatment protocol. There was no significant difference between the two groups on admission with regard to recognized criteria of poor prognosis. The octreotide-treated group required significantly less analgesia and after 48 hr developed significantly fewer poor prognostic indicators, including falls in hematocrit of > 10%, in serum albumin to < 32 g/liter, and in serum calcium to < 2.00 mmol/liter. Falls in arterial PO2 to < 10 kPa, in serum albumin of > 20%, and in hemoglobin of > 2 g/dl were also significantly less frequent. There was a trend towards improvement in the octreotide-treated group in every other physiological and radiological indicator of disease severity. High-dose octreotide may reduce the severity of acute pancreatitis.