To compare the effectiveness of flutamide and spironolactone plus Diane 35 in the treatment of idiopathichirsutism (IH). Design: Prospective randomized clinical study. Setting: Social Security Agency, Aegean Obstetrics and Gynecology Teaching Hospital, Department of Reproductive Endocrinology and Infertility, a tertiary referral center. Patient( s): Eighty women with IH who had been admitted to our center. Intervention(s): Patients were randomly and equally assigned to receive flutamide (250 mg/d for the first 10 days of the cycle) and spironolactone plus Diane 35 (spironolactone 100 mg/d; Diane 35 is a combination tablet of 2 mg cyproterone acetate and 35 μ g ethinylestradiol/d) for 9 months. Main Outcome Measure(s): Modified Ferriman-Gallwey (F-G) score and hormonal profile before treatment and at the end of treatment. Result(s): In spite of the fact that there were no statistically significant differences in modified F-G scores in between the two groups, a significant decrease in modified F-G scores was observed in the flutamide (from 19.93 ± 4.31 to 15.58 ± 4.28)-and spironolactone plus Diane 35 (from 18.77 ± 3.76 to 14.54 ± 3.29) groups. There were also no differences between the two groups with respect to hormonal profiles including serum FSH, LH, free T, 17- OH-progesterone, and DHEAS levels. No major side effect, including liver toxicity, was observed in either group. Conclusion(s): Our data suggest that both therapies have similar effectiveness in the treatment of IH. To compare the effectiveness of flutamide and spironolactone plus Diane 35 in the treatment of idiopathic liverism (IH). Design: Prospective randomized clinical study. Setting: Social Security Agency, Aegean Obstetrics and Gynecology Teaching Hospital, Department of Reproductive Endocrinology and Infertility, a tertiary referral Patient (s): Eighty women with IH who had been admitted to our center. Intervention (s): Patients were randomly assigned equally and receive equally flutamide (250 mg / d for the first 10 days of the cycle) and spironolactone plus Diane 35 (spironolactone 100 mg / d; Diane 35 is a combination tablet of 2 mg cyproterone acetate and 35 μg ethinylestradiol / d) for 9 months. Main Outcome Measure (s): Modified Ferriman- Gallwey (FG) score and hormonal profile before treatment and at the end of treatment. Result (s): In spite of the fact that there were no significant significant differences in modified FG scores in between the two groups, a significant decrease in m Odd FG scores were observed in the flutamide (from 19.93 ± 4.31 to 15.58 ± 4.28) -and spironolactone plus Diane 35 (from 18.77 ± 3.76 to 14.54 ± 3.29) groups. There were also no differences between the two groups with respect to hormonal profiles including serum FSH, LH, free T, 17-OH-progesterone, and DHEAS levels. No major side effect, including liver toxicity, was observed in either group. Conclusion (s): Our data suggest that both therapies have similar effectiveness in the treatment of IH.