In patients with liver disease, the synthesis of drug-binding proteins may be impaired. After liver transplantation, levels of drug-binding proteins are unknown. Consequently, concentrations of albumin and α-acid glycoprotein (AAG) were measured in stable patients after liver transplantation. Albumin levels were decreased from normal (4.5 ± 3 gm per dl) in patients with liver disease before (3.4 ± 0.7) and after transplantation (3.4 ± 0.8). AAG levels were decreased from normal (67 ± 20 mg per dl) in patients with liver disease (46 ± 22) but were higher than normal after transplantation (121 ± 28). AAG is an acutephase reactant, the synthesis of which may have been stimulated by the surgical procedure. The effect of these changes on drug metabolism was not studied.