Eleven of twenty-four patients with severe aplastic anemia given marrow grafts from HLA-identical siblings between October 1970 and March 1973 are alive with normal marrow function and continued evidence of engraftment 3–5 yr later. Ten have been leading normal lives with no immunosuppressive or other drug therapy since day 100 postgrafting. One has had chronic graft-versus-host disease of the skin which is now slowly improving with no therapy. He returned to full-time employment in the summer of 1975. The long-term well-being of almost half of our initial patients emphasizes the importance of marrow transplantation for the treatment of severe aplastic anemia.