I. IntroductionIt is estimated that at least seven percent of the adult population in the United States are alcoholics or abuse alcohol (1). Considering the extent of the alcohol problem it is obvious that a basic understanding of the medical consequences of alcohol use and abuse is important. Gonadal dysfunction, as evidenced by decreased libido and impotence in the nonalcoholic drinker and infertility with gonadal atrophy in the alcoholic individual, is one of the more common problems. Data regarding the site or sites and the mechanisms of alcohol-induced gonadal and hypothalamic-pituitary toxicity are often conflicting. This article reviews our current knowledge about the effects of ethanol on male gonadal function. II. Evidence for Gonadal Failure and Estrogen Excess in Men with Alcoholic CirrhosisClinical gonadal failure, characterized by impotence, loss of libido, infertility, and testicular atrophy, is commonly observed in chronic alcoholics with cirrhosis of the liver. In addition, there are signs suggestive of estrogen excess including gynecomastia, cutaneous vascular abnormalities, increased concentrations of sex hormone binding globulin and changes in body hair and fat distribution. Laboratory tests in these individuals reflect multiple alterations in the hypothalamic-pituitary-gonadal axis, as well as changes in the hepatic handling of sex steroids (2–7). Alcoholic men without cirrhosis also show varying degrees of hypogonadism and hyperestrogenism both clinically and chemically (8–11).