Current concepts of testosterone metabolism in the human skin are reviewed, and the role of dihydrotestosterone in the pathophysiology of androgenetic alopecia, acne vulgaris, and idiopathic hirsutism is discussed. The hypothesis is submitted that a temporary, increased dihydrotestosterone formation at specific skin target sites at different ages causes the normal development of certain sexual characteristics, as well as the androgen-dependent skin disorders. Future treatment of these conditions is discussed in light of recent studies with antiandrogens.