Obscure gastrointestinal bleeding is a relatively frequent disorder and may account for as many as 5% of all cases of gastrointestinal bleeding. The etiology of these hemorrhages may be attributed to lesions in the small intestine, which may not show up in radiologic studies, located in areas inaccessible to conventional endoscopy. The case of a 50-year-old patient admitted to the hospital on two occasions for gastrointestinal bleeding requiring blood transfusions is reported. On the first occasion, the bleeding was thought to be caused by a duodenal ulcer because no other lesions prone to bleeding were found. At the next admission for recurrent bleeding, the ulcer was found to have healed and thus was ruled out as the cause. Wireless capsule endoscopy detected an ulcerated tumor invading the submucosa of the jejunum. The pathologic diagnosis was low-grade leiomyosarcoma. Wireless capsule endoscopy has proved to be far superior to other radiologic and endoscopic techniques for the diagnosis of obscure gastrointestinal bleeding and pathologies of the small intestine in general.