Five male members in four generations of the same family had hypogonadism, gynecomastia, mental retardation, obesity, and short stature. The X-linked mode of inheritance, the distinctive facies, the normal size of the hands and feet, and the true gynecomastia are the main characteristics. Endocrine evaluation and histologic studies of the testes suggest partial hypogonadotropic hypogonadism. This disorder represents a new syndrome distinct from others previously described.