Primary small intestinal lymphoma is relatively uncommon. Small bowel tumors are difficult to diagnose, because they are usually asymptomatic in the initial phase, and they are not easily detected by traditional methods of investigating the small intestine. This case shows a successfully detected and treated gastrointestinal bleeding from rare ileal mucosa-associated lymphoid tissue lymphoma, using double balloon endoscopy. (Korean J Gastroenterol 2013;62:365-369).