AbstractBackground:Upper gastrointestinal (GI) endoscopic abnormalities are common in symptomatic bone marrow transplant (BMT) recipients but the incidence of occult gastrointestinal disease in these patients is unknown.Aims:To examine the role of screening upper GI endoscopy before and after BMT.Methods:Endoscopy was performed routinely on allogeneic (n = 24) and autologous (n = 17) BMT patients before transplant and at 30 and 120 days after transplant.Results:Twenty‐one of 41 patients (51%) had an endoscopic abnormality on one or more occasions which necessitated a change in treatment. These abnormalities were present in ten of 41 (24%) pre‐transplant endoscopies, ten of 32 (31%) endoscopies at day 30 after BMT, and in seven of 22 (32%) day 120 endoscopies. Abnormalities included mucosal erosions or ulcers (n = 22 endoscopies), infections (n = 5) or previously undiagnosed GI graft‐versus‐host disease (n = 3). Mucosal erosions or ulcers were present in eight of 28 endoscopies despite regular anti ulcer drug therapy.Conclusions:Screening upper GI endoscopy before and after BMT is generally safe and detects a high yield of significant GI abnormalities. However, it remains to be demonstrated that treatment of these lesions will improve the clinical outcome in BMT recipients without GI s