Abdominal aortic aneurysm (AAA) enlarges after successful endovascular repair, because of persistent blood flow within the aneurysm sac, or endoleak. In the absence of detectable endoleak, AAA may still expand, in part because of persistent pressurization within the excluded aneurysm, or endotension. We report three patients who underwent successful endovascular AAA repair in whom postoperative surveillance showed aneurysm regression, yet delayed AAA enlargement without demonstrable endoleak developed in all three patients. Endotension was confirmed in all three patients at elective open conversion. Our study underscores the significance of endotension as a mechanism of delayed aneurysm enlargement after successful endovascular AAA repair.