AbstractVarious estimates abound as to the incidence of conjoined (Siamese) twins, but they are indeed uncommon. The probability of their occurance has been calculated to be once in every 12,000 to once in every 100,000 deliveries. Although uncommon, the antepartum diagnosis can be extremely important to the twins and the mother, if only to spare the trauma of a trial by labor. The findings, both radiographic and ultrasonic, are presented herein.