The penetration of imipenem into the human pancreatic juice following a single intravenous dose of 500 mg was investigated in five patients who had undergone pancreatic transplantation. With a special technique for segmental pancreatic transplantation it was possible to collect pure pancreatic juice at regular intervals. Simultaneous blood and pancreatic juice samples were collected immediately before drug administration and then at 0.5, 1, 1.5, 2.5, 3.5 and 5.5 h thereafter. The antibiotic concentrations were determined by the agar diffusion method. The mean peak level in serum was 24.6 +/- (SE) 2.6 mg/l and occurred 0.5 h after administration. The mean peak concentration in pancreatic juice was not reached until 1.5 h after administration, and the level was then 1.7 +/- (SE) 0.3 mg/l. Thereafter the levels in serum and pancreatic juice declined in parallel, and the concentration in pancreatic juice was then about 13% of that in serum. Although imipenem penetrates into the pancreatic juice at a very low degree, the concentrations exceeded the MIC values for many bacteria associated with pancreatic infections. Imipenem could therefore be an alternative as monotherapy in the treatment of pancreatic infections.