An animal model which permits sampling of arterial blood and bile from unanesthetized rats with uninterrupted enterohepatic circulation is described. Pharmacokinetic data concerning inulin (0.2 mumol kg-1) and terbutaline (1.8 mumol kg-1) after intraarterial injection are presented. The following values for inulin were obtained Vdbeta equals 0.25 ml g-1, plasma clearance equals 2.3 ml min-1 kg-1 and bile clearance equals 0.03-0.04 ml min-1 kg-1, which mainly are in agreement with data from the literature. For terbutaline the corresponding values were 0.58 ml g-1, 5.2 ml min-1 kg-1 and 0.12-0.98 ml min-1 kg-1, respectively.