Ratinale: Penetrating aortic ulcer (PAU) and rupture of a superior mesenteric artery branch is a rare but potentially life-threatening condition. Patientconcerns: We describe a case of 73-year-old man was brought to our Emergency Department for intermittent back pain. Diagnoses: The final diagnoses are PAU (Stanford B) and rupture of a branch of the superior mesenteric artery. Interventions: Two covered stents were placed in the thoracic aorta and the right external iliac artery, and the superior mesenteric artery branch was embolized. The patient subsequently underwent exploratory laparotomy, where 6000 to 7000mL of intraabdominal hematoma was evacuated. Outcomes: After the operation, the patient recovered smoothly and was discharged 20 days later. During 3-year follow-up, the patient did not develop any pain or discomfort. Lessons: Acute aortic syndrome (AAS) and acute coronary syndrome (ACS) may be difficult to distinguish, particularly for elderly patients with extensive atherosclerotic disease. Antithrombotic agent administration should be carefully considered.