Serum testosterone, prolactin, LH, FSH and plasma 17 beta-oestradiol levels were determined in forty-seven male patients with sexual impotence. Low testosterone values and slightly elevated prolactin levels were observed in 19% and in 17% of cases, respectively. Since sexual function in the male seems to be controlled by both dopaminergic stimulatory and serotoninergic inhibitory mechanisms, bromocriptine was given orally to seventeen patients. As the preliminary results appeared encouraging, a double blind study was undertaken in the other thirty patients. No appreciable difference in hormonal pattern was noticed between bromocriptine and placebo treatment. As far as sexual function was concerned, good results were obtained in 52% of cases treated with bromocriptine and in 44% of patients given placebo.