We studied the immune reconstitution and incidence of chronic graft-vs-host disease (GVHD) and infection in 25 patients who survived more than 1 year after bone marrow transplantation (BMT) from unrelated donors for treatment of leukemia. Of the 25 patients, 4 died after 1 year post-transplantation. The causes of death were relapse of leukemia (2 patients), obstructive bronchiolitis (1 patient), and hepatic failure (1 patient). Only 2 of 14 patients who were under 30 years of age at the time of their BMT developed chronic GVHD, however, 7 of 11 patients 30 years of age or older developed chronic GVHD. Lower karnofsky scores were displayed by 6 of the older patients with chronic GVHD but by none of the younger patients with chronic GVHD. These results underscored the importance of care for older patients with chronic GVHD.CD4-positive T cells, and especially CD4 * CD45RA-positive T cells, had not recovered to a normal range even 2 years after BMT. Longer follow-up will be necessary.