purpose: To describe the incidence, presentation, clinical course, and management of avascular necrosis of bone following bone marrow transplantation, and to identify risk factors related to its development and outcome. patients and methods: All patients developing avascular necrosis after transplantation between March 1974 and May 1988 were identified by means of the Minnesota Bone Marrow Transplant Database and hospital records and included in analysis. Of 902 consecutive patients undergoing bone marrow transplantation, 28 developed avascular necrosis of bone. results: Twenty-eight of 642 allogeneic transplant recipients (10.4% by product limit estimate) developed avascular necrosis compared to zero of 260 autologous transplant recipients. Symptoms developed 1 to 62 months (median 12 months) after transplantation. In the 28 patients a total of 91 joints were affected (mean 3.3 per patient, range one to eight joints). The hip joint was most often involved (64% of patients), followed by knee (61%), ankle (29%), shoulder (21%), and elbow (7%). Initial standard radiographs were negative in 13 patients, while in nine patients, technetium-99 scans and/or magnetic resonance imaging demonstrated changes of osteonecrosis before changes on routine radiographs. Almost all patients had received steroid prophylaxis and therapy for graft-versus-host disease (GVHD). We observed a significant correlation between the total cumulative dose of steroids and number of joints involved (p <0.01). A multivariate analysis (allogeneic transplant patients only) identified acute or chronic GVHD requiring steroid therapy (p = 0.003), and increasing age (p = 0.002) as significant and independent risk factors. Fourteen patients required surgery, including joint replacement in 11 patients. In six of six patients, hip core decompression failed to halt disease progression, and total hip arthroplasty was subsequently required. conclusion: Avascular necrosis of bone is a frequent late complication of bone marrow transplantation, causing significant morbidity and often requiring surgery; diagnosis using conventional imaging techniques may be difficult and treatment remains inadequate.