Alopecia in the male is considered as a genetically determined disorder. Increased local androgen metabolism and androgen receptor binding in the balding areas confirm the importance of the target organ hair follicle as regulative of androgen influences. In our study the hormonal parameters of 65 male patients with male pattern hair loss with a mean age of 24.31 years were compared with those of 58 age-matched controls. Determinations of the androgens, sex-hormone-binding globulin, the hypophyseal hormones luteinizing hormone, follicle-stimulating hormone and prolactin, 17 beta-estradiol and cortisol were performed by standard radioimmunoassay. Significant differences in serum levels of androstenedione, cortisol, 17 beta-estradiol and luteinizing hormone were noted between hair loss patients and control subjects. Suprarenal stimulation as well as hypophyseal feedback mechanisms therefore seem to be involved in male pattern alopecia.