We report a case of fetal hydrops and mirror syndrome in a pregnancy with anti-Jra alloimmunization.A 34-year-old multiparous woman (G3P2) at 29 weeks of gestation had complications which included generalized edema and mild dyspnea. An indirect Coombs test was positive for anti-Jra antibodies. A blood examination showed hemodilution and elevated human chorionic gonadotropin. An ultrasound examination showed fetal hydrops with cardiomegaly and polyhydramnios. The patient delivered a pale and edematous infant by cesarean section and laboratory tests showed that the neonate had severe anemia (Hb 4.4 g/dL). A direct Coombs test was also positive. Microscopic examination of the placenta revealed diffuse villous edema. A genetic test for the ABCG2 gene showed the homozygous point mutation c.376C > T (376TT) in the mother, while her three offsprings all exhibited 376CT heterozygosity.The potential risk of severe fetal hydrops and mirror syndrome should be recognized in pregnancies with anti-Jra alloimmunization.