The effects of intravenously administered octreotide (5 or 10 micrograms/kg body weight) on pyloric, duodenal, colonic, pancreatic, and islet blood flow were investigated with a microsphere technique in anesthetized rats. The lower dose of octreotide reduced only pyloric blood flow, while the higher dose caused a reduction also in duodenal and colonic blood flow. Whole pancreatic blood flow was not affected by either of the doses of octreotide, but the blood flow through the islets was decreased by the higher dose. Also, the fraction of whole pancreatic blood flow through the islets was decreased by the higher dose. It is concluded that octreotide mainly affects intestinal blood flow, but not whole pancreatic blood flow in rats. However, octreotide causes a redistribution of the blood flow within the pancreas, which leads to a diminished islet blood perfusion, in conjunction with a decrease in serum insulin concentration.