Twenty-seven patients (age range from 1 to 55 years) were included in a cooperative bone marrow transplantation program in Stockholm. Of eight patients with severe aplastic anemia (SAA), two died following graft rejection and six (75%) are alive between 3 months and 4 1/2 years after transplantation. Two patients with end stage leukemia died of septicemia and bleeding shortly after transplantation. Thirteen of 17 patients (76%) with acute leukemia in their first or second remission are alive 1 to 16 months after transplantation. Death was caused by septicemia in two patients, interstitial Candida pneumonitis in one and gastrointestinal bleeding in association with graft-versus-host disease in one. Among the leukemic patients all deaths occurred in subjects over 17 years of age and all 10 children are alive. No relapse has yet been seen. Successful bone marrow transplantations were carried out utilizing ordinary hospital resources only. This justifies the practice of performing transplantations in subjects with SAA and acute leukemia in remission even outside specially equipped and designed bone marrow transplantation units.