From 1982 to 1994, 54 patients (47 men; mean age 72 years) were referred to the Hospital of Ferrara, Italy for spontaneous rupture of abdominal aortic aneurysm. Sixteen died in the emergency department and 38 underwent urgent surgery. Day and month of onset of acute symptoms leading to urgent surgery were recorded. A seasonal variation with significant peaks in spring and autumn was found. These findings are likely influenced by local environmental, social and epidemiological factors, but may be relevant for the appropriate timing of the follow-up and therapeutic strategies for abdominal aortic aneurysms.