Certain oxygenated derivatives of cholesterol have dramatic effects on cholesterol synthesis. The present study compared the effects of cholesterol and an oxygenated metabolite, cholesterol-α-epoxide, on sterol metabolism in rats. Sterol balance measurements using isotopic and chromatographic techniques were carried out in rats fed liquid control diets, control diets + cholesterol (1 mg/ml), and control diets + cholesterol-α-epoxide (1 mg/ml). Sterol metabolism was affected by both cholesterol and cholesterol-α-epoxide. Cholesterol feeding decreased cholesterol synthesis (−9.57 ± 7.23 mg/day), increased endogenous bile acid synthesis (7.71 ± 1.18 mg/day), and increased cholesterol turnover (7.78 ± 2.33 mg/day) compared to controls. Cholesterol-α-epoxide had no effect on cholesterol synthesis, endogenous bile acid synthesis and cholesterol turnover compared to controls. However, animals fed cholesterol-α-epoxide had large increases in total acidic steroid output (determined by chromatographic analysis, 12.23 ± 4.05 mg/day). This finding suggests that cholesterol-α-epoxide is absorbed and converted to bile acids. Apparently, the epoxide enters the bile acid biosynthetic pathway distal to the rate-limiting step of 7α-hydroxylation. As a result, large amounts of bile acids are formed from the epoxide without affecting endogenous cholesterol or bile acid synthesis. This was confirmed in a separate experiment by feeding [4- 14C]cholesterol-α-epoxide and recovering labeled bile acids (hyodeoxycholic acid and lithocholic acid) as well as the starting radioactively labeled epoxide in the feces.