The presence of PP1Pk antibody is considered a main cause of repeated spontaneous abortions in early pregnancy. Because PP1Pk antibody generated in maternal blood may disturb the feto-maternal environment, plasmapheresis is supposed to be a beneficial method of lowering PP1Pk antibody levels in women with blood group-incompatible pregnancies. Double filtration plasmapheresis (DFPP) was used to treat feto-maternal P-incompatible pregnancy. The successful use of DFPP to treat a pregnant Japanese woman is presented. This method is a useful treatment for group P women who have not been able to deliver a live infant. Copyright (C) 2003 S. Karger AG, Basel.