Bleeding from a Zenker's diverticulum is rare. A 71-year-old man was urgently admitted with massive hematemesis. It was known that he had a Zenker's diverticulum, but on emergency endoscopy, the source of bleeding was not detected due to large blood clots in the esophagus, hypo-pharynx and also into the tracheal-bronchial tree. Computerized tomography angiography demonstrated a blush of intravenous contrast arising from the diverticulum. The patient was operated upon urgently; the diverticle had a deep ulceration which was the source of the bleeding. The cause of the ulceration is unknown but it is possible that it was caused by the direct effect of an aspirin pill within the diverticle. A similar case with the same conclusion has been published in the past and since the use of aspirin has become common, especially in the elder population, we present this case report to highlight this possible life-threatening complication of Zenker's diverticulum in patients receiving aspirin.