Gastric bleeding due to graft-vs-host-disease (GVHD) is rare after allogeneic hematopoietic stem cell transplantation, and the interrelationship between endoscopic and histologic assessment has not been well studied. Four patients with documented gastric bleeding due to GVHD were evaluated retrospectively. The endoscopic findings varied markedly and included mild mucosal edema with focal erythema, diffuse erythema with mucosal oozing, and diffuse polypoid indurations with multiple bleeding ulcerations. The histologic features of endoscopic biopsy specimens also varied from scattered apoptotic epithelial cells in one end to denudation of the epithelium with crypt necrosis in the other. The endoscopic findings could not accurately predict the histologic grading of GVHD. Nevertheless, gastric bleeding resolved in 3 patients with increasing intensity of immunosuppression. There was significant disparity between the endoscopic and histologic assessment of the severity of GVHD, and careful adjustment of immunosuppressive therapy might be warranted.