A new biphasic oral contraceptive (OC) containing ethinylestradiol and desogestrel (DGS) in both phases of the cycle (7 days 40/25 micrograms + 15 days 30/125 micrograms) was tested for its reliability, tolerability, safety and effectiveness on endocrine correlates of hyperandrogenism and acne in normal women (n = 30) and women suffering from acne (n = 33). Contraceptive efficacy was absolute and, despite 3 drop-outs in the group with acne (4.7% of total patients), subjective complaints were limited to a small number of women. Cycle control was satisfactory in both groups. Fibrinopeptide A remained stable under the treatment, whereas HDL-chol increased and the ratio between LDL-chol and HDL-chol decreased during pill intake. Other advantageous effects were obtained on the circulating androgen profile with increased sex hormone binding globulin concentrations coupled with significantly reduced total and free testosterone levels. In 23 out of 30 patients with acne (76.6%) the skin disease disappeared after 9 months of therapy and in 3 severely affected subjects the pathology changed into a pattern of mild or moderate degree. Our results indicate that the tested new biphasic OC combination is reliable, well tolerated, safe and effective against hyperandrogenism.