A bioartificial liver (BAL) is a medical device entrapping living hepatocytes or immortalized cells derived from hepatocytes. Many efforts have already been made to maintain the functions of the hepatocytes in a BAL device over a long term. However, there is still some uncertainty as to their efficacy. and their limitations are unclear. Therefore, it is important to quantitatively evaluate the metabolic functions of a BAL. In previous studies on in vitro BAL devices, two test methods, an initial bolus loading and constant-rate infusion plus initial bolus loading, were theoretically carried out to obtain physiologic data on drugs. However, in the current study, the same two methods were used as a perfusion model and derived the same clearance characterized by an interrelationship between the perfusate flow rate and intrinsic clearance. The interrelationship indicated that the CL increased with an increasing perfusate flow rate and approached its maximum value, i.e. intrinsic clearance. In addition, to set up an in vivo BAL system, the toxic plateau levels in the BAL system were calculated for both series and parallel circuit models. The series model had a lower plateau level than the parellel model. The difference in the toxic plateau levels between the parallel and series models increased with an increasing number of BAL cartridges.