Purpose: The purpose of this study is to evaluate the factors affecting the endoleaks of endovascular aneurysm repairs in infrarenal abdominal aortic aneurysms. Methods: On a retrospective basis, we analyzed 122 patients, who underwent endovascular aneurysm repair (EVAR) for infrarenal abdominal aortic aneurysm between March, 2006 and June, 2011. According to the endoleak, the patients were divided into 2 groups: endoleak group and non-endoleak group. We compared the following variables between the 2 groups: patient clinical characteristics (age, gender, body mass index, history of smoking, hypertension, diabetes mellitus, and coronary artery disease) and anatomical features of the aneurysms. Results: A total of 111 male and 11 female patients were included. Fifty-two patients showed endoleak (42.6%) during follow-up periods (median: 4.6 years). There was no significant difference between endoleak and non-endoleak group according to patient's clinical characteristics and used devices. However, there were significant differences between two groups according to the anatomical features of the aneurysm, such as the morphology, size of the aneurysm, and the size and angle of the neck of the aneurysm. Conclusion: Endoleak indicated high frequency when the aneurysm size is large, and when the neck aneurysm is large, with the neck angle being more than 60 degrees. Thus, patients with more than one of the above three characteristics may need more attentive and cautious procedures as well as a closer follow-up.