Incorporation of 14C-acetate into 3-beta-OH sterols and of 3H-leucine into proteins was examined in liver biopsies from patients with liver disorders. Biopsies obtained from patients in whom no liver disease was found served as controls. Reduced 14C-acetate incorporation into sterols was found in biopsies from patients with chronic active hepatitis and primary biliary cirrhosis. Stimulated incorporation of 3H-leucine into proteins was demonstrated in patients with alcoholic liver cirrhosis and in patients with ulcerative colitis associated with liver disease. No correlation could be established between serum proteins and lipids, respectively, on the one hand, and between incorporation of precursors into proteins and sterols, on the other. 'Incorporation parameters' were also inferior to conventional liver tests when used in the differential diagnosis between different liver disorders by discriminant analysis. Our findings may suggest, however, that hepatic sterol synthesis is frequently decreased in patients with chronic active hepatitis and primary biliary cirrhosis.