Type II endoleaks after endovascular repair of abdominal aortic aneurysm (EVAR) are a result of retrograde flow from arterial branches (e.g., lumbar and inferior mesenteric) refilling the aneurysm sac, which has been excluded by the stent graft. Controversy continues with regard to the clinical significance and treatment of type II endoleaks. To develop recommendations for management, we analyzed outcome data from 10 EVAR trials completed over the last 5 years involving a total of 2,617 cases. The incidence of type II endoleak at discharge or 30 days was 6-17%, at 6 months 4.5-8%, and at 1 year 1-5%. Successful resolution of endoleak following secondary interventions was observed in 11-100% of cases. There were 10 conversions to open repair and no ruptures related to type II endoleak. In patients observed for 12 months with computed tomography and/or ultrasound, approximately one-half of type II endoleaks disappeared spontaneously. In the absence of a type I endoleak, our analysis of the current literature suggests that intervention for type II endoleak should be undertaken for abdominal aortic aneurysm sac enlargement occurring after 6 months, persistence for >12 months without abdominal aortic aneurysm sac enlargement, or an aneurysm sac pressure >20% of systolic blood pressure; translumbar aneurysm sac thrombosis and intra-arterial feeding vessel occlusion appear to be prudent management options.