Androgenic stimulation of sebaceous glands is an important factor in the development of acne. We examined 36 females (aged 14-34 years), selected because none had received oral contraceptives, anti-androgen therapy, or systemic antibiotics during the previous year, or isotretinoin therapy, prior to their participation in the study. Subjects were divided into groups on the basis of acne severity, as follows: physiological, mild and moderate. Only two patients had polycystic ovaries on ultrasound examination. Seven patients had irregular menses; none had evidence of hirsutism. We found that the severity of acne, based on the acne grade, was highly correlated with the inflammatory lesion count, and less correlated with the sebum excretion rate. Either acne grade or inflammatory lesion count could be related to some of the five androgenic hormone determinants; free testosterone (TESTOS), delta 4 androstenedione (DELTA 4), sex hormone binding globulin (SHBG), dehydroepiandrostenedione sulphate (DHEAS) and dihydrotestosterone (DHT). Multiple linear regression analysis determined the best model for predicting ACNE scores as involving DELTA 4 and DHEAS (positive effects), and SHBG (negative effect), P < 0.005, R2 = 0.36). In none of the patients were the levels of DHEAS or SHBG outside the normal range. The findings in the two patients with polycystic ovaries did not differ significantly from those in the remainder of the patients.