Seventeen patients (15 men and two women) underwent operation for concomitant abdominal aortic aneurysm (AAA) and colorectal carcinoma (Ca) during a recent 12-year period. Ages ranged from 59 to 89 years (median 75.2 years). Diameter of the AAA ranged from 3.5 to 9.5 cm (median 5.5 cm). The Ca was staged by the Astler-Coller modification of Dukes' classification as B1 in three patients, B2 in eight, C2 in three, D in two, and unclassified in one. Personal preference, presence of symptoms, and extent of malignant involvement determined preference of resection. The Ca was eventually resected in 16 patients and the AAA in nine. Thirteen patients underwent resection of the Ca first, two the AAA first, and two concomitantly. Eight patients (47%) underwent resection of both the AAA and Ca, eight underwent resection of the Ca only, and one underwent resection of the AAA only. There were three deaths in 24 operations. Follow-up ranged from 5 weeks to 8 years (median 1 1/2 years). Only five patients (29.4%) were long-term survivors without evidence of recurrent Ca and all occurred in the eight patients (62.5%) who had undergone resection of both the Ca and AAA. Three late deaths occurred as a result of complications from the unresected AAA in the eight patients who had undergone resection of the Ca only (37.5%). We conclude that if the Ca is not symptomatic and localized the AAA should be resected first. However, both lesions need to be resected eventually for long-term survival.