Backgrouud/Aims: Primary biliary cirrhosis (PBC) is an autoimmune disease of the liver with inflammation of small and middle-sized bile ducts. Serum lipids are frequently elevated, but the use of a lipid lowering drug therapy in PBC is still a matter of debate. Application of an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in hypercholesterolemic PBC patients was therefore the subject of the present study. Methods: Six female patients (aged 46.5 (32-61) years; median (range)) were treated with the HMG-CoA reductase inhibitor simvastatin (5 or 20 mg/day). Levels of serum total cholesterol, low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol were determined prior to and after 2 months of treatment. Concentrations of serum markers of cholestasis, antimitochondrial antibodies (AMA), and immunoglobulins A, G and M were also assessed. Results: Simvastatin significantly (P < 0.05) reduced serum levels of total cholesterol, LDL cholesterol, alkaline phosphatase, γ-glutamyltransferase, and immunoglobulin M (by 19, 26, 12, 37 and 14%, respectively). Conclusions: The lipid lowering potency of the HMG-CoA reductase inhibitor simvastatin was confirmed in hypercholesterolemic patients with PBC. The drug might also prove useful as modulator of cholestasis and of immune response in this disease. (C) 2002 European Association for the Study of the Liver. Published by Elsevier Science B.V. All rights reserved.