Upper gastrointestinal bleeding is a frequent syndrome in the elderly that requires urgent attention. The main causes of melenas are peptic ulcer (gastric or duodenal) and esophageal diseases (esophagitis, esophageal varices and Mallory-Weiss syndrome). Unusually, upper gastrointestinal bleeding may be due to a duodenal tumor. Gastrointestinal stromal tumors (GIST) are included in this group. We report the case of an 81-year-old woman who presented with melenas. Gastrointestinal endoscopic studies (upper and lower) revealed no abnormalities, and a duodenal mass was found on thoracic-abdominal computed tomography scan. Urgent surgery due to a massive bleeding episode led to diagnosis of a duodenal GIST.