Synthesis of35S-labeled taurocholic acid was studied in dogs with a gall bladder fistula kept on a high-cholesterol diet (2 g/kg). In the first period (1–2 months) of feeding on a high-cholesterol diet a marked increase in the synthesis of [35S]taurocholic acid was observed. After 5–6 months, in the period of development of the pathological process in the liver, the synthesis and secretion of bile acids and the formation of a cholesterol residue in the bile were reduced. The serum cholesterol level in these dogs was increased but not significantly.