Persistent Müllerian duct syndrome (PMDS) is a type of male pseudohermaphroditism that results from a quantitative, qualitative or temporal deficiency of the male anti-Müllerian Hormone (AMH) or its receptor during prenatal development and retention of the Müllerian derivatives. PMDS patients are genotypic and externally phenotypic males with cryptorchidism, sometimes associated with inguinal hernia. To our knowledge there is only one previous report of PMDS in association with Klinefelter's syndrome (KS). We report on a 44-year-old patient who was referred for genetic counseling after being evaluated for lower abdominal pain, swelling, dysuria and hematuria; apparently he had right sided inguinal hernia and bilateral cryptorchidism. Echosonography and pelvic CT could not distinguish the nature of the cystic formation positioned between urinary bladder and rectum, above prostate. Hormonal findings showed high gonadotropins, low testosterone and normal estrogen. Genetic workup showed positive sex chromatin, positive SRY gene and 47, XXY karyotype. Patient was normally virilized, but azoospermic male with normal intelligence. The patient was surgically treated; the cystic formation was in fact uterus with an atrophic testis on one side and soft tissue structure on the other side. This case raises questions of possible underestimation of KS patients who have Müllerian remnants due to inadequate testicular function, overestimation of normal karyotypes in PMDS patients as well as question of presumably increased testicular malignancy in PMDS patients. Further genetic analysis of the AMH and AMH receptor genes is necessary.