RATIONALE: Hemosuccus pancreaticus (HP) is a rare but serious cause of gastrointestinal bleeding, characterized by hemorrhage from the papilla of Vater via the pancreatic duct. It is typically associated with vascular or pancreatic pathologies, including pancreatic cysts, tumors, or pseudoaneurysms involving adjacent arteries such as the splenic or gastric artery. PATIENT CONCERNS: A 68-year-old male patient was evaluated for a pancreatic tail cyst detected on magnetic resonance cholangiopancreatography (MRCP). The lesion was described as a 20-mm multilocular cystic formation with septations, raising suspicion of malignancy. DIAGNOSIS: HP was diagnosed following an episode of gastrointestinal bleeding after endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) of the pancreatic tail cystic lesion. INTERVENTIONS: The patient underwent EUS-FNA via a transgastric approach to obtain a tissue sample for further evaluation. OUTCOMES: The procedure was complicated by gastrointestinal bleeding and later confirmed to be HP. The bleeding was managed conservatively, and the patient remained hemodynamically stable with spontaneous resolution of symptoms. LESSONS: This case underscores a rare but significant complication of EUS-FNA. Given the limited number of reported cases, further research is needed to establish the incidence, risk factors, and preventive measures for HP in similar clinical scenarios.