A 45,X/46,Xidic(Y)(q11.2) mosaicism was found in a 4-year-old boy. The clinical appearance was characterized by bilateral cryptorchidism, penoscrotal hypospadias, short penis, and coarctation of the aorta. The latter is the only abnormality also seen in Turner syndrome. A biopsy of the gonads revealed normal prepubertal testicular tissue. A chromosome analysis in all boys with penoscrotal, scrotal, or perineal hypospadias and a thorough examination of the heart in children with 45,X/46,XY mosaicism are recommended.