Between 1981 and 1986, 282 cases of abdominal aortic aneurysm were diagnosed in Waltham Forest. Rupture had occurred in 183, 15 underwent urgent operation for intact aneurysm, and 84 had elective surgery. The incidence of rupture increased from 13 to 21 per 100000 population during the 6-year period. Operative mortality for patients with rupture was 54.7 per cent, but the mortality overall was 81.4 per cent. In 59 per cent of patients with rupture no operation was performed, and 35.0 per cent of all deaths occurred in the community. The mortality for rupture in women was significantly higher than in men, although the operative mortality was comparable. Fifty patients (27 per cent) were found to have attended hospital within 2 years of rupture and many had documented evidence of an aneurysm. One-third of all patients admitted with rupture were undiagnosed. This study complements the previous small number of community studies and suggests that the incidence of rupture is increasing nationally particularly in women, where the mortality was exceptionally high. Early elective surgery is the key to the problem and improved clinical awareness could save many patients without elaborate and expensive programmes to screen the ‘at risk’ population.