Five women with exaggerated sex urge were treated with large doses (25 mg.) of testosterone propionate, administered by subcutaneous injection at varying intervals. All patients experienced rather prompt relief which, however, was temporary. In three patients repeated courses of injections were followed by repeated periods of success. One patient failed to respond after initial relief, although she did remain somewhat less perturbed. A psychopathic nymphomaniac was relieved but complained of being desexed.Experiments stressing the gonadal inhibiting effect of testosterone propionate are described and the effects of this hormone on the pituitary gland are cited. The mechanism of action is discussed and it is concluded that testosterone propionate, when given in excess depresses the anterior pituitary gonadotropic function sufficiently to lessen the sex urge of the individual.Abstract Teaser