The effects of dose of metoprolol (Met) on hepatic elimination was studied in isolated rat liver perfused at a flow of 25 ml.min-1. The results showed that Met was eliminated by rat liver in accordance with one-compartment model. Linear kinetic eliminating processes (apparent first-order kinetics) were found in doses of Met 0.2, 0.5, 1.0, and 2.0 mg, T1/2 were 8.3, 8.8, 9.6, and 10.6 min and the clearance rate were 11.7, 11.8, 9.6, and 8.6 ml.min-1, respectively. Nonlinear eliminating processes were found in doses of Met 4, 8, and 12 mg. Vm and Km were 0.98, 1.05, and 0.94 microgram/min-1.ml-1 and 15.6, 16.9, and 14.6 micrograms.ml-1, respectively. It is concluded that hepatic Met elimination is independent on lower doses, but rested upon high doses.