The major function of platelets is to contribute to hemostasis. If an impairment in their production and/or function occurs, abnormal bleeding can develop. An 18-year-old male presented to our hospital after four episodes of hematemesis. His medical history was relevant for Glanzmann thrombasthenia diagnosed during early childhood. On initial examination, he appeared pale and with normal blood pressure. His complete blood count included a hemoglobin concentration of 11.0 g/dL, additional laboratory tests were within the normal ranges. The initial approach consisted of a high dose of proton pump inhibitors. Hours later, esophagogastroduodenoscopy revealed diffuse oozing bleeding from gastric mucosa with no other visible lesions such as peptic ulcers or varices.