We experienced two cases of abdominal aortic aneurysm which had intra-abdominal malignancy (early gastric cancer). Case 1 was a 72 year-old man who was treated by two-stage operation of them. Gastrectomy was performed about 7 months prior to the aneurysmectomy. Case 2 was a 70 year-old man who was diagnosed both lethal diseases, renal dysfunction, chronic respiratory failure and multiple ventricular arrhythmia. He was treated by one-stage operation and was discharged with no complications. Coexistence of abdominal aortic aneurysm and intra-abdominal malignancy is rare and it is difficult to decide whether to operate the malignancy first, the aneurysm first or both simultaneously. In Japan, 28 cases were reported and 18 cases could be analyzed in detail. In these cases, most frequent coincidental malignancy was the gastric cancer (13/18, 72.2%) and one-stage operation was performed in 8 (44.4%) cases. In general, the risk of infection during upper gastrointestinal surgery is less than that during lower abdominal surgery. We concluded therefore that concomitant resection of the upper gastrointestinal malignancy, especially early gastric cancer, should be considered.