The effects of flutamide (25 mg / kg, intragastric, daily, for three days) on bile formation in male rats were investigated. The volume rate of bile secretion decreased in male rats under the influence of flutamide. It was found a significant reduction of the glycoconjugated bile acids concentration in the bile of the male rats under flutamide action. So, glycochenodeoxycholate and glycodeoxycholate concentration in the bile are significantly lower (16,3 – 34,5 %) in male rats under the flutamide action than in bile samples of the control group animals. But it was found that flutamide does not change the ratio of the total conjugated bile acids to unconjugated bile acids. Flutamide inhibits hydroxylation of bile acids in the male rats. The coefficient of the bile acids hydroxylate is decreased under the influence of flutamide compared to control by 10,1%. Thus, flutamide decreases bile flow, conjugation of the bile acids with glycine and glycoconjugates transport into the bile.