PURPOSE: To evaluate on abdominal CT the type and incidence of various complications of abdominal aortic aneurysm (AAA). MATERIALS AND METHODS: Twenty six suspected cases of AAA were confirmed by operation(n=21) and by CT(n=5). The etiology, size, shape and incidence of various complications of AAA were then retrospectively evaluated. In addition, post-operative complications were also evaluated in five cases. RESULTS: The etiology ofthe aneurysm was atherosclerotic in 18 cases and mycotic in three ; it showed the presence of Behcet disease in three cases, of tuberculosis in one, and of Marfan syndrome in one. Among the 18 fusiform AAA, the mean maximum diameter of ruptured AAA(7.5±3.3cm, n=3) was significantly larger than that of unruptured AAA(4.9±1.6cm, n=15)(p<0.05). The saccular type was much more likely to rupture than the fusiform type(p<0.00001). Out of the eight saccular AAA, seven ruptured ; their mean maximum diameter was 3.9±1.3cm This was significantly smaller than that of ruptured fusiform aneurysm(p<0.05). The most common complication was rupture, and occurred ten of 26 cases(38%). Others included hydronephrosis in three cases, bowel infarction in one, and perianeurysmal retroperitoneal fibrosis in one case. Various post-operative complications developed in five patients ; these comprised periprosthetic pseudoaneurysm with hematoma (two cases), bowel ischemia (one), focal renal infarction(one), and secondary aorticoduodenal fistula (one). CONCLUSION: The most common complication of AAA was rupture, the rate of which was much higher in the saccular type with smaller size than the fusiform type. Other various and uncommon complications were observed. CT was helpful in detecting complications arising from AAA and in planning its treatment.