OBJECTIVE We determined the natural history of the residual native infrarenal aortic segment after conventional abdominal aortic aneurysm (AAA) repair. METHODS For the retrospective arteriographic case series, 800 hundred translumbar aortograms (TLAs) were obtained for 272 patients, before and after conventional AAA repair. The main outcome measures were changes in the aortographic diameter and the length of the infrarenal aortic segment, corrected and uncorrected for magnification by normalization to the first lumbar vertebral body height. RESULTS The mean follow-up time from the preoperative TLA to the most recent postoperative TLA was 42 months (range, 1 to 257 months). Vertebral body height did not change (p = 0.35). The length of the native infrarenal aorta cephalad to the proximal anastomosis increased a mean of 3 mm, from 23 to 26 mm (p = 0.001). However, in 115 patients (43%), this aortic segment elongated more than 5 mm, and in 63 patients (24%), it elongated more than 10 mm. The native residual infrarenal aorta above the proximal anastomosis dilated a mean of 1 mm, from 23 to 24 mm (p = 0.001), but in 21 patients (8%), it dilated more than 5 mm. There was a weak positive correlation between the increase in residual native aortic diameter and duration of follow-up. There was a negative correlation between this increase and the initial size. The diameters of the proximal anastomosis and proximal graft did not change. Marked variability in the changes in aortic dimensions was observed. CONCLUSIONS A mean period of 42 months after conventional AAA repair, the native infrarenal aortic segment elongates and dilates. Although such enlargement is statistically significant, the average increase appears to be small. However, residual aortic cuff diameter increased more than 5 mm and neck length more than 10 mm in a significant number of patients, with potentially serious implications for endovascular treatment of AAA.