Abstract： Objective To explore the clinical value of color Doppler ultrasonography in diagnosing twin reversed arterial perfusion sequence (TRAP)and improve early diagnosis of this rare fetal malformation. Methods From January 1995 to September 2008, 19 TRAP were diagnosed or suspected by prenatal ultrasonography in our hospital. The final diagnosis was confirmed by ultrasound after birth or autopsy. Relative information of the 19 cases were collected and analyzed retrospectively. Results Among the 19 TRAP fetuses, all the recipients bad severe and lethal developmental abnormalities. Prenatal ultrasonography was highly accurate in demonstrating skin edema, spine, abdominal organ and lower limbs, but found difficulty in cranial dysplasia and microsoma upper limbs and was not able to demonstrate facial malformations. Among the 19 donors, 3 survived and 16 died. Cardiac insufficiency was detected in 9 cases. The structural features of fetal appendages incluced: (1) All alive recipients were supplied by umbilical artery draining towards the fetus, which was different from normal fetus. (2) Abnormal placental vascular anastomoses was found between the two fetuses. (3) The cord of the recipient, the acardiac fetus, had single umbilical artery. (4) Polyhydramnios predicted poor prognosis. (5) Entanglement and knot of umbilical cord usually happened in monoamniotic twins. Conclusions Color Doppler ultrasonography could provide important information in evaluating the hemodynamics characteristics of TRAP, cardiac function of the donor fetus, abnormalities of fetal appendages and in predicting prognosis and is the first choice for prenatal diagnosis of TRAP.