Nine patients with severe Rh iso-immunization were treated by plasma exchange combined with immunosuppression. Apart from 3 abortions, previous pregnancy losses consisted of 7 intra-uterine and 5 neonatal deaths. Only 2 patients had had no previous pregnancy loss. Differences in the optical density of the amniotic fluid of 8 patients fell into the upper Liley zone. There was one intra-uterine death due to abruptio placentae but no neonatal deaths. When the outcome of the pregnancy immediately preceding the treatment pregnancy was compared to the treatment pregnancy, the fetal loss was reduced from 6 to 1. No adverse fetal effects were encountered.