PURPOSE: To evaluate the features of magnetic resonance(MR) imaging of bone marrow (BM) following bone marrow transplantation (BMT). MATERIALS AND METHODS: Eighteen BMT recipients (8 severe aplastic anemia and 10 leukemia patients) underwent MR imaging. Fourteen were males and four were females, and their mean age was 27.2 years. Allogeneic transplantation was performed in 14 patients, unrelated transplantation in three, and peripheral blood stem cell transplantation in one. The mean interval between BMT and MR examination was 22.7 weeks. MR imaging was performed using a 0.5 T superconducting MR unit(Gyroscan T5, Phillips, Netherlands). Signal intensity(SI) on T1 weighted (T1WI) and short tau inversion recovery(STIR) images of lumbar vertebral BM, and on T1WI of pelvic BM, was analyzed with respect to that of muscle. RESULTS: In nine patients in whom BMT was successful, the SI of lumbar vertebral BM was low to slightly high on T1WI and iso to low on STIR images. Six patients with labile engraftment syndrome and two relapsed patients showed inhomogeneous high SI with scattered low signal areas on T1WI and variable SI on STIR images. In particular, in patients who had relapsed, the SI seen on STIR images was high. One patient in whom rejection had occurred showed homogeneous high SI on T1WI and low SI on STIR images of lumbar vertebral BM. The SI of pelvic BM, as seen on T1WI, was inhomogeneously high, irrespective of engraftment status. The SI of pelvic BM showed a larger high-signal portion than did lumbar vertebral BM seen on T1WI. CONSLUSION: MR imaging of lumbar vertebral BM was useful for the evaluation of BM status after BMT. Engraftment of the pelvis might be delayed compared to that of the lumbar vertebrae.