Background. To evaluate on the basis of our experience in 12 patients with chronic contained rupture (CCR) of an abdominal aortic aneurysm, the aetiopathogenesis of the disease, its clinical presentation, its diagnosis and the results of surgery. Methods. From January 1990 to June 1999 a total of 768 patients underwent surgery for abdominal aortic aneurysm: 662 (86.2%) were operated electively and 106 (13.8%) in emergency. Six hundred and fifty- four (85.1%) patients presented an aneurysm without fissuration or rupture (Group A), 102 (13.3%) showed a fissured aneurysmatic sac (Group B) and 12 (1.6%) presented CCR (Group C). Age, gender, risk factors, associated vascular disease and outcome of surgery were compared in the three groups and the anatomic and clinical characteristics of patients with CCR were examined. Results. No statistically significant differences were found between the 3 groups for risk factors or associated vascular disease. Patients with CCR are often normotensive and show smaller retroperitoneal haematoma compared to patients in Group B. Operative mortality in Groups A, B and C was respectively 3, 41.2 and 8.3%. Conclusions. Owing to its possible evolution into free rupture, CCR calls for rapid diagnosis and treatment. CT is the most reliable means of diagnosis. Patients with CCR are more often normotensive and present smaller retroperitoneal haematomas compared to ruptured aneurysm. Retroperitoneal drainage is recommended, together with bacterial culture of the haematoma and more frequent postoperative controls to prevent graft infection.