Abstract Objectives: it has been suspected that the position at which aneurysm rupture occurs would affect outcome. The aim of this prospective study was to relate the morphology of the ruptured abdominal aortic aneurysm (RAAA) to the clinical characteristics and outcome of the patient.Design, patients and methods: over a five-year period 46 patients with RAAAs (11 identified at operation and 35 at post-mortem (PM)) were examined to identify the number and site of aneurysm rupture, the characteristics of the aneurysm (site, shape, length, diameter and associated iliac aneurysm) and the presence and site of retroperitoneal or intraperitoneal haematoma. The patients were also assessed for a range of associated medical conditions. Univariate analysis was used to identify variables predicting the site of aneurysm rupture and survival following rupture.Results: most aneurysm ruptures (73%) occurred in the middle third where the aneurysm diameter was greatest. Relatively few ruptures (13%) were in the left posterior quadrant of the aneurysm. A history of chronic lung disease (p =0.04) significantly predicted the quadrant of aneurysm rupture, while a history of carcinoma (p =0.02) predicted the level of rupture. Nine of the 46 (20%) patients survived. Survival was predicted by the transverse site of rupture (p =0.0004) and the absence of ischaemic heart disease (p =0.02).Conclusion: these data suggest that the site of aneurysm rupture, which may be in part predicted by the clinical characteristics of the patient, influences outcome.