In this study, 12 women and 12 men, ages 18-33 y, with androgenetic alopecia were selected for biopsies from frontal and occipital scalp sites. The androgen receptor, type I and II 5alpha-reductase, cytochrome P-450-aromatase enzyme were measured and analyzed in hair follicles from these scalp biopsies. Findings revealed that both women and men have higher levels of receptors and 5alpha-reductase type I and II in frontal hair follices than in occipital follicles, whereas higher levels of aromatase were found in their occipital follicles. There are marked quantitative differences in levels of androgen receptors and the three enzymes, which we find to be primarily in the outer root sheath of the hair follicles in the two genders. Androgen receptor content in female frontal hair follicles was approximately 40% lower than in male frontal hair follicle. Cytochrome P-450-aromatase content in women's frontal hair follicles was six times greater than in frontal hair follicles in men. Frontal hair follicles in women had 3 and 3.5 times less 5alpha-reductase type I and II, respectively, than frontal hair follicles in men. These differences in levels of androgen receptor and steroid-converting enzymes may account for the different clinical presentations of androgenetic alopecia in women and men.