One-stage surgical management of concomitant abdominal aortic aneurysm (AAA) and gastric or colorectal cancer should provide certain benefits. We reviewed the records of 21 patients with both AAA and gastric or colorectal cancer who underwent one-stage surgical management. Four had distal gastrectomy, 2 had total gastrectomy, and 5 had abdominoperineal rectal resection transperitoneally; 3 had total gastrectomy transperitoneally and AAA repair extraperitoneally. Two underwent right hemicolectomy and thromboexclusion of the AAA. Two had creation of a temporary ileostomy and implantation of an interposition graft. Two underwent left hemicolectomy, creation of a temporary transversostomy, and implantation of an interposition graft. One had a Hartmann's procedure and implantation of a bifurcated prosthetic interposition graft for AAA. There were no operative deaths or serious postoperative complications. One patient had colorectal ischemia that resolved with conservative treatment. Eighteen of the 21 patients (85.7%) were alive 10 months to 14 years postoperatively. In conclusion, one-stage surgical treatment of concomitant AAA and gastric or colorectal cancer is well tolerated and can avoid the time, financial costs, and patient anxiety involved in a second operation.