The small intestine is by far the most difficult area to study from an endoscopic point of view, since traditional endoscopy only covers up to the 2nd portion of the duodenum and colonoscopy up to the terminal ileum. On rare occasions we find it necessary to use non-traditional endoscopic equipment to be able to study this middle area of the small intestine. Gastrointestinal stromal tumor is one of the neoplastic differential diagnoses found at this level. Given the advancement of genetics associated with immunohistochemistry, we have been able to better evaluate and characterize these lesions of mesenchymal origin. A case of a jejunal gastrointestinal stromal tumor with an initial presentation of melena is presented. Where together gastroenterology, surgery and pathology, the mentioned final diagnosis was reached.