Four cases of ruptured abdominal aortic aneurysms as a postoperative complication are reported. This represents a 24 per cent mortality for elective operation in patients with known abdominal aortic aneurysm. Three cases followed resection of abdominal malignancy. The possibility exists that subtle trauma during operative manipulation may have heightened the risk of rupture. The risk to life from large abdominal aortic aneurysms (more than 6 cm) exceeds the risk of most malignancies. Abdominal aortic aneurysm should be resected first when co-incidental to a malignancy, unless the malignancy is complicated by hemorrhage, obstruction or perforation.