Although many patients now survive the short-term complications of bone marrow transplantation for life-threatening hematologic disease, information on the health and activity of long-term survivors is sparse. To evaluate the morbidity and mortality of patients surviving more than 5 years after allogeneic bone marrow transplantation. Retrospective, multicenter study. 798 recipients of bone marrow transplants (477 adults, 321 children) from 43 European centers. Patients had received transplants before December 1985 and had survived at least 5 years. Patients had received allogeneic or syngeneic bone marrow for leukemia, lymphoma, inborn diseases of the hematopoietic and immune systems, and severe aplastic anemia. Survival, clinical performance according to Karnofsky score (in increments of 10%), and social reintegration were assessed as outcomes. Patient age and sex, primary disease and status at transplantation, histocompatibility of the donor, conditioning regimen, type of prophylaxis of graft-versus-host disease, and acute and chronic graft-versus-host disease were evaluated as variables. For the 55 5-year survivors, actuarial mortality was 8% at 10 years and 14% at 15 years. The leading causes of death were disease recurrence (21 patients), chronic graft-versus-host disease with complicating infections and lung disease (11 patients), secondary cancer (8 patients), and the acquired immunodeficiency syndrome (AIDS) (5 patients). When patients with recurrent disease were excluded, late death was associated with chronic graft-versus-host disease (P < 0.001), occurrence of secondary cancer (P < 0.001), male sex of the patient (P = 0.05), and female sex of the donor (P = 0.002). Clinical performance was normal (Karnofsky score, 100%) or minimally reduced (Karnofsky score, 90%) in 93% of patients; 89% of patients resumed full-time work or school. Reduced performance status and incomplete resumption of social activity were associated with chronic graft-versus-host disease, recurrent leukemia, AIDS, secondary cancer, organ dysfunction, and neurologic or psychological problems. Other risk factors for incomplete resumption of social activity were female sex (P = 0.002) and older age at transplantation (P = 0.001). More than 5 years after bone marrow transplantation, most patients were in good health (93%) and had returned to full-time work or school (89%). Recurrence of the primary disease, secondary cancer, and chronic graft-versus-host disease and its sequelae remain problems for some patients.