Over a 3-year period, 44 ultrasound-guided intravascular transfusions were performed between 18 and 32 weeks on 15 patients with severe erythroblastosis fetalis due to Rh immunization. In 4 fetuses, the first transfusion was performed before 20 weeks, in 6 between 20 and 25 weeks and in the remaining 5 between 25 and 31 weeks. Eight of the 15 fetuses were hydropic at the time of referral. Five transfusions were done in the intrahepatic umbilical vein, 6 were simple transfusions via percutaneous umbilical cord puncture, and 33 were partial exchange. There were 4 intrauterine deaths before 26 weeks, despite successfully performed tranfusions: 3 of these fetuses were severely hydropic, while in the remaining fetus hydrops had been reversed in utero. Following delivery by cesarean section at 32 weeks of gestation, 1 of the neonates developed respiratory distress syndrome and died 17 h after birth. The overall survival rate was 67% (10 of 15 cases): 4 of the 8 hydropic fetuses (50%) and 6 of the 7 nonhydropic fetuses (83%) were alive at birth and survived the perinatal period. Three of the 5 losses occurred among the first 4 cases, while in the last 11 cases the survival rate increased to 82% (9 of 11).