The antiandrogen effects of an oral contraceptive containing 0.03 mg. Ethinyl Oestradiol and 0.15 mg. Desogestrel have been evaluated in 17 non-obese hirsute women, with normal serum LH and FSH values and their ratio, and evidence for Micropolycystic Ovary Syndrome (MPCO) on ultrasound examination. At the completion of 5 cycles (21 days) of treatment, a statistically significant decrease in serum Total Testosterone, Free Testosterone, Androstenedione levels was observed. Similarly, serum values for Dehydroepiandrosterone Sulphate and 17-OH-Progesterone showed a marked fall. The Sex Hormone Binding Globulin (SHBG) values rose about four-fold, so that the Free Androgen Index was suppressed. The clinical score, evaluated according to the method of Ferriman and Gallwey, was found sharply reduced. Therefore, the well defined improvement of biochemical and clinical parameters, along with the absence of discernible side effects, are undoubtedly confirming the effectiveness of the treatment in hyperandrogenism of women with MPCO.