True hermaphroditism was revealed by monthly intrascrotal bleeding in a 21-yr-old subject of male phenotype who had undergone surgical treatment for gonadal ectopy at the age of 7 yr. The presence of an ovary was demonstrated by the endocrine profile of an ovulatory menstrual cycle. Evidence for the presence of a testis was provided by a plasma testosterone increase after hCG administration (5000 IU/day for 3 days) and its spontaneous response to an endogenous preovulatory LH peak. Further endocrine studies revealed that both gonads were stimulated by endogenous gonadotropins. At surgery, a hemiuterus and an ovary with corpus luteum were found in the left hemiscrotum, and a testis and epididymis were found in the right hemiscrotum. After removal of the ovary, the subject passed from a predominantly female to a male endocrine status, which suggests that the endocrine secretion of the testis was inhibited by the negative feedback effect of ovarian steroids on gonadotropin secretion.