A rare but typical case of trisomy 9 mosaicism is reported. The infant showed the characteristic phenotype of this syndrome: low-set malformed ears, micrognathia, broad nose with bulbous tip, abnormal brain, congenital heart disease, abnormal hands and feet, cryptorchidism, micropenis, and early death. This infant, however, did not have dislocation of joints or microcephaly; the head was larger than normal and had almost a cloverleaf shape.