PURPOSE: To evaluate the MR findings of gastrointestinal graft-versus-host disease (GVHD) after allogenic bone marrow transplantation. MATERIALS AND METHODS: Five patients (M:F=3:2, age range: 9-58 years) with suspected gastrointestinal GVHD underwent abdominal MRI, and the findings were evaluated. Because of acute myelocytic leukemia (n=4) or non-Hodgkin's lymphoma (n=1), all had undergone allogenic bone marrow transplantation 2-6 (mean, 3.5) weeks earlier. T2-weighted half-Fourier acquisition snapshot turbo spin-echo, T1-weighted spoiled gradientecho (SGE), and postcontrast T1-weighted SGE MR imaging, with and without fat-suppression, was performed. RESULTS: All five patients showed bowel wall thickening and marked contrast enhancement in the jejunum (n=5), ileum (n=4), duodenum (n=3), sigmoid colon (n=3), gastric antrum (n=2), and rectum (n=2). Bowel wall thickening showed a target appearance in the jejunum (n=2, 40.0%), ileum (n=1, 25.0%), sigmoid colon (n=1, 33.3%), and rectum (n=1, 50.0%), while the remaining cases showed diffuse wall thickening without layering. Small amount of ascites was noted in four patients (80%), and multiple small conglomerated retroperitoneal lymph nodes in three (60%). In all patients, a signal intensity of slightly enlarged liver due to iron overload secondary to multiple blood transfusions, gave rise to decreased signal intensity at both T1-and T2-weighted MR imaging. CONCLUSION: In patients with GVHD, the commonly noted MR findings were bowel wall thickening with contrast enhancement, ascites and retroperitoneal lymphadenopathy.