The TRAP sequence is a rare anomaly seen in 0.3-1% of all monochorionic twin gestations. One of the twins is acardiac and acts like a parasite. The normal co-twin pumps blood for the other through abnormal vascular communications in the placenta. It is lethal for the acardiac fetus and also poses a high risk of morbidity and mortality for the ‘pump’ fetus secondary to anemia, high-output cardiac failure and prematurity. The sonographic prenatal diagnosis is important for proper management. This case has been presented to remind that the TRAP sequence is a rare and serious anomaly and to emphasize the importance of ultrasonographic examination as a simple but adequate tool in the diagnosis, follow-up, and even in the treatment of such a case

Keywords: Acardiac twin, TRAP sequence, Ultrasonography