Serum levels of sex hormones were measured in adult patients with atopic dermatitis (AD) and compared with those in sex- and age-matched healthy controls. In 40 male patients with AD, serum levels of testosterone (T) (447 +/- 96 vs 593 +/- 149 ng/dl, P < 0.001), free testosterone (FT) (14.6 +/- 3.2 vs 20.0 +/- 5.1 pg/ml, P < 0.001) and estradiol (E2) (27.2 +/- 7.2 vs 33.2 +/- 7.9 pg/ml, P < 0.05) were significantly lower and serum levels of luteinizing hormone (LH) (4.57 +/- 1.6 vs 3.11 +/- 1.2 mIU/ml, P < 0.001) were significantly higher than those in healthy controls. There were no significant differences in serum levels of dihydrotestosterone (DHT), dehydroepiandrosterone sulfate (DHEA-S), dehydroepiandrosterone (DHEA), or follicle stimulating hormone (FSH) between the two groups. In 25 female patients with atopic dermatitis, T, FT, DHT and DHEA-S levels did not differ from controls. In conclusion, serum T levels were lower in male patients with AD. However, similar changes were not seen in female patients.