Cytomegalovirus (CMV)-induced interstitial pneumonitis is a well-known lethal complication in bone marrow recipients. CMV is also known to cause gastroenteritis. We report the first case of a bone marrow recipient who developed CMV-induced gastritis which is verified both histologically and virologically. The gastritis preceded the interstitial pneumonitis which was detected in an early stage and was successfully treated. We propose that bone marrow recipients who show signs and symptoms of gastritis undergo an endoscopic examination, and that biopsied specimens should be scrutinized for CMV by both histological examination and culture investigation.