Background. Surgical resection remains the only curative procedure for liver metastases but even in expert hands it has appreciable morbidity and mortality rates. The presence of a concomitant aortic aneurysm greatly increases these risks. Case outline. A 66-year-old woman who was known to have large aneurysms of the thoraco-abdominal aorta and middle cerebral artery presented with colorectal liver metastases. After detailed preoperative assessment, she underwent resection of segments V and VI of the liver. The surgical procedure was uneventful. She made a good initial recovery, but on day 7 she suddenly became hypotensive and died from a cardiorespiratory arrest. Post-mortem examination revealed a ruptured thoracic portion of the thoraco-abdominal aortic aneurysm. Conclusion. Despite careful control of perioperative blood pressure and the lack of abdominal complication, intrathoracic aneurysmal rupture on day 7 highlights the risk of major unrelated operations in patients with aneurysmal disease.