Hormonal parameters (see below) were determined in 78 male acne patients of both sexes (mean age 21.2 +/- 3.8 years; (mean +/- S.D.) and compared with 63 controls (25.0 +/- 4.2 years). In a female group consisting of 60 patients acne (23.2 +/- 5.0 years) and 28 controls (26.1 +/- 5.7 years) of age, blood sampling was performed in the luteal phase of the menstrual cycle. Testosterone (T), dehydroepiandrosterone-sulfate (DHEAS), androstenedione (A), free testosterone (FT) and 17-hydroxy-progesterone (17-OHP) were determined by standard radioimmunoassay methods. In addition, sex hormone binding globulin (SHBG), follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), 17 beta-estradiol (E2) and cortisol (F) were evaluated. Moreover, the counts of acne lesions in the face were performed in 34 males and females patients in order to investigate possible correlations between hormones and acne lesions. The results in the male group revealed a significant elevation only for F but not for the other hormones. However, the female acne group significantly elevated levels of T, DHEA and F and a decrease of E became apparent. In addition, the correlation between both free and total T and acne lesions were found in the total of males and females. In the female group, free T and total A were found to correlate with acne lesions. The evaluation of these results indicates that androgens play a more important role in female than in male acne at the hormonal and at the peripheral level in skin. Another interesting finding was the significant increase of F in both male and female acne subjects, thus stressing the role of suprarenal involvement.