Whole pancreatic blood flow (PBF) and islet blood flow (IBF) were measured 5 min after administration of glucose at serum glucose concentrations ranging between 8.5 and 25 mM. The serum insulin concentration increased proportionally (p less than 0.01) to the serum glucose concentration. PBF was unaffected by i.v. glucose administration at 5 min, while IBF increased in proportion to the serum glucose concentration of the animals in the range of 8.6-16.7 mM. No further increases in IBF could be seen at higher glucose concentrations. It is concluded that glucose preferentially stimulates IBF and that this increase, to a major extent, is due to a redistribution of flow within the gland.