The decision on whether to operate or not abdominal aortic aneurysms (AAA) in elderly depends on the relative risk of the operation versus the natural course of the unoperated AAA. From January 1984 to December 996, 138 patients, aged 80 years and older, were referred to our department for an aneurysm of 40 mm or more (transverse diameter) of the infrarenal abdominal aorta (95 asymptomatic, 15 painful, and 28 ruptured AAA). For 58 patients with asymptomatic AAA, operation was denied at referral because of transverse diameter less than 50 mm (n = 21), patient refusal (n = 10) or unacceptable operative risk or poor general condition (n = 27). Thirty-four of these observed AAA were ultimately operated after a mean delay of 41 months because of aneurysm enlargement (n = 15), aneurysm tenderness (n = 6) or rupture (n = 13). Overall, 52 patients had immediate (n = 37) or delayed (n = 15) elective repair of their AAA, with an in-hospital mortality of 5.7%. Urgent operation was done for 21 patients with a painful AAA. Six patients died at hospital (28% mortality rate). Emergent surgery was applied to 41 patients with ruptured AAA (including 13 AAA who ruptured during surveillance). The operative mortality in this subgroup attained 68%. Follow-up for the 77 survivors and the 24 non-operative patients averaged 43 months. The 5-year survival (operative mortality included) is 47% for electively operated patients, 30% for urgently and 20% for emergently operated patients. For comparison, the 5-year survival of an age and sex matched Belgian population is 63%. For the 24 medically followed AAA, the 5-year survival was 33%. In six cases, the cause of death was rupture of the AAA. Of the 58 patients for whom operation was initially not considered, 19 (33%) presented AAA rupture (13 operated in emergency and 6 who never came to surgery). The operative outcome of AAA repair in octogenarians is less favourable than in the younger age group (3.6% mortality after elective repair, 44% after operation for AAA rupture, according to our institution data). The authors conclude that AAA surgery should not be denied to octogenarians on the basis of advanced age alone. They recommend a straightforward surgery for otherwise healthy octogenarians with AAA of 50 mm diameter, surveillance up to 60 mm for high-risk patients and no surgery for unfit, bedridden or demented patients.