Hepatic dysfunction is a frequent finding in sepsis and peritonitis. In the present study, hepatic function in experimental peritonitis in the rat was determined by measuring serum levels of bilirubin, alkaline phosphatase (ALP), glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT), together with antipyrine (AP) clearance as a determinant of microsomal function. Peritonitis was induced by intraperitoneal injection of 3 x 10(8) colony-forming units of E. coli together with either 1.0 ml bile or saline. E. coli + bile peritonitis rats had significantly elevated levels of bilirubin, ALP, GOT and GPT as compared with both controls and rats with peritonitis induced by E. coli alone. The derangements gradually increased with time over the 10-hour period studied. In contrast, no reduction of AP clearance was observed in the peritonitis models. On the contrary, AP clearance was enhanced at 10 hours after induction of peritonitis by E. coli alone. In conclusion, hepatic dysfunction as revealed by routine laboratory tests is seen early in experimental peritonitis in the rat, but this is not accompanied by a reduced AP clearance rate.