1. A case of paroxysmal nocturnal hemoglobinuria is presented which developed hemoglobinuria for the first time while in the hospital and showed severe reactions to whole blood transfusion but none to washed red cells.
2. Therapeutic administration of heparin induced severe hemoglobinuric episodes which were followed by a remission in the transfusion reactions to whole blood.
3. Later, aplastic anemia developed with a marked subsidence in the various indicators of the hemolytic process although the erythrocytic defect found in paroxysmal nocturnal hemoglobinuria was still present.