Two placentas in singleton pregnancy with fused umbilical cord which has its own placental insertion site forming 3-vessel cord at fetal end is an extremely rare case. This present case describes two placentas with fused umbilical cord with an episode of vanishing twin syndrome and there seems to be a strong relationship between these two events. A 37-year-old woman, gravid 0, para 0, visited emergency room with an episode of vaginal bleeding without pelvic cramps at 8 weeks and 5 days of gestation and repeated ultrasonic exams revealed reabsorption of vanishing twin and two separate placentas on anterior and posterior body of uterus. At 40 weeks and 4 days, the patient delivered a viable female infant weighing 3,900 g via Cesarean section and postpartum examination of the placentas and membranes confirmed two placentas with fused umbilical cord. Two placentas were almost equal in size and there were 2 cord insertions, 1 into each placenta. The cord at each of the placental disc had marginal insertion site and main placental disc cord had 2 arteries with one vein (3 vessel-cord) whereas side placental disc cord had one artery with one vein (2 vessel-cord). Several hypothesis for this two placentas with fused umbilical cord in singleton pregnancy, were proposed including placenta abnormalities after in vitro fertilization-embryo transfer procedure, succenturiate lobes and fetus in fetus, however, further evaluation is need.