The etiology of male-pattern alopecia is explained as an interrelationship of three factors, genetic—a single dominant sex-limited gene; endocrine—dihydrotestosterone is the specific hormone responsible; and age. Other factors previously used to explain male-pattern alopecia are de-bunked. Treatment today is directed in the area of endocrinology, basically using either antiandrogens that block 5-α-reductase, thus preventing the formation of dihydrotestosterone, or steroids that interfere with dihydrotestosterone cytosol-nuclear binding protein expression.