We report on a 5-year-old girl with a male karyotype (46,XY), severe psychomotor and physical retardation, minor anomalies, and female external genitalia with a blindly ending vagina. She has normal adrenal function, prepubertal serum gonadotropin and testosterone levels, which did not rise after hCG stimulation. On abdominal exploration no gonads were found, and only mesonephric and Müllerian remnants. She was HY positive, and no deletion was detected in the Y chromosome using 5 different probes. Although a genetic defect is not excluded, pregnancy complications suggest an environmental insult to the developing testes.