['The aim of the study was to determine whether type II endoleak (T2E) after endovascular repair of abdominal aorta (EVAR) is a benign condition (ie, not associated with growth, reintervention, rupture, or death).', 'Data from patients who underwent EVAR for atherosclerotic infrarenal aortic aneurysms between June 1995 and May 2010 in the Vascular Surgery Department of Henri Mondor Hospital were prospectively collected. Data from patients presenting with at least one T2E on computed tomography scan during their follow-up were compared with those with no T2E. Three subcategories of T2E were studied according to time of occurrence (early or late), persistence (persistent or transient), and recurrence (recurrent or not recurrent).', 'Seven hundred patients were included with follow-up ranging from 1 month to 15 years (median, 31.3 months; range, 12.4-61.4); 201 (28.9%) had at least one T2E. Patients with T2Es were significantly older (P < .001), female (P = .015), had larger aneurysms (P = .019), and patent lumbar arteries (P = .003). Patients without T2Es had a higher incidence of current smoking (P < .001) and chronic obstructive pulmonary disease (P < .005). Multivariate analysis showed risk of T2E was increased in older patients (odds ratio [OR], 1.04; confidence interval [CI], 95% 1.02-1.06; P < .001) and in those with patent lumbar arteries (OR, 1.70; CI, 95% 1.16-2.50; P = .007), and was reduced in active smokers (OR, 0.16 CI, 95% 0.04-0.71; P = .015) or patients with coronary artery disease (OR, 0.65; CI, 95% 0.45-0.92; P = .016). Patients with T2Es had more complications (death, rupture, reintervention, or conversion) (P < .001) and greater aneurysm sac enlargement (>5 mm upon follow-up) (P < .001). Multivariate analysis showed T2E was a risk factor for aneurysm diameter growth >5 mm; this risk was increased if T2E persisted more than 6 months (hazard ratio [HR], 3.16; CI, 95% 2.55-6.03; P < .001), was recurrent (HR, 1.88; CI, 95% 1.18-3.01; P = .008), or associated with a type I or III endoleak (HR, 1.96; CI, 95% 1.41-2.73; P < .001). Recurrent T2E was associated with a higher rate of reintervention (P = .04) and conversion to open surgery (P = .028).'] Are type II endoleaks after endovascular repair of abdominal aortic aneurysm always a benign condition?