The role of intrauterine transfusion for fetal hydrops arising from maternal paravirus B19 infection is unclear. 66 cases of fetal hydrops arising from B19 infection were reported in England and Wales between June, 1992, and September, 1994. In 29 cases the fetus was dead at the time of the first abnormal ultrasound or a therapeutic abortion as performed; 12 of the 38 alive at the first abnormal scan received intrauterine transfusions and 3 of the 12 died. 26 did not receive intrauterine transfusions and 13 died. After adjustment for the severity of the hydrops as assessed by the ultrasound and for gestational age, the odds of death among those who received an intrauterine transfusion was significantly less than among those who did not (odds ratio 0·14, 95% Cl 0·02-0·96). These findings suggest that intrauterine transfusion will benefit some fetuses with hydrops arising from parvovirus B19 infection.