An acutely thrombosed abdominal aortic aneurysm (AAA) is a rare but devastating complication of aortic aneurysms. Incidence in reported series is approximately 0.7-2.8% of surgically managed AAA cases with an associated mortality rate of 50%. To date there have been only 46 cases of acutely occluded AAAs reported in the literature. We present our experience of 2 additional cases of acute AAA thrombosis and discuss the mechanism of thrombosis and management. The size of the aneurysm seems to be a better predictor of rupture than of thrombosis. Strong risk factors for thrombosis are the presence of concomitant iliac artery and cardiac disease. Although this complication is rare, its high mortality rate makes it an important disease to understand, recognize, diagnose, and treat for a successful outcome.