Danazol is a synthetic attenuated androgen that can interfere with normal interactions between the pituitary-hypothalamic axis and the gonads. These effects are mediated by complex mechanisms, including those in which danazol can compete with natural steroids in binding to androgen receptors or to sex hormone-binding globulin, possibly displacing natural steroids from this protein, and in binding to reactive sites of enzymes required for synthesis of natural steroids, thereby depressing synthesis. Because of danazol's impairment of the pituitary-hypothalamic interactions with gonads, it is an effective therapeutic agent for treatment of endometriosis and cystic disease of the breast. It is effective in the treatment of hereditary angioneurotic edema, but the mechanism of this therapeutic success is unclear. Danazol has been used, without universal success, in the treatment of other gynecologic and certain hematologic disorders.