The disappearance of IV injected [24-14C] cholic acid from plasma was studied in normal and mutant Corriedale and Southdown sheep exhibiting hereditary defects in hepatic organic anion transport. Hepatic cholic acid clearance was determined from the integral of the 40-minute disappearance curves fit to the sums of two exponential functions. Cholic acid clearance among Corriedale sheep was significantly less (P less than 0.05) for mutant sheep (8.44+/-0.86 SEM ml/minute/kg of body weight) than for normal sheep (12.7+/-0.58 ml/minute/kg). Cholic acid clearance in the Southdown mutant (1.97+/-0.59 ml/minute/kg) was less than 15% of normal clearance rate (13.3+/-2.2 ml/minute/kg). Clearance of [14C] taurocholic acid (curves fit to three exponential function) in the Southdown mutant (10.8+/-0.4 ml/minute/kg) was significantly greater (P less than 0.01) than cholic acid clearance, yet was not significantly different (P greater than 0.05) from normal taurocholate clearance (17.8+/-2.5 ml/minute/kg). Hepatic regurgitation of conjugated bile acid was not detected after [14C] cholic acid injection. Both the mutant Corriedale and Southdown sheep, which exhibited inherited defects in hepatic bilirubin transport similar to Dubin-Johnson syndrome and Gilbert's disease in man, exhibited defects in hepatic bile acid clearance.