Case report of a 49-yr. old true hermaphrodite. The external genitals appeared masculine; the patient had been reared as a male and had male psyche. Gynecomastia and female hair distr., absence of sperm, small prostate and urinary gonadotropins of 157 M. U./24 hrs. all suggested Kleinfelter''s syndrome. Urinary 17-ketosteroids were 1 mg./24 hrs. Autopsy showed a right testis in the scrotum, with increased Leidig and Sertoli cells and absent spermatogenic series. On the left, an ovary, uterus and vagina without external opening were found. The ovary had corpora albicantia, and the uterus had glandular endometrium. The pituitary showed acidophile proliferation.