This is to report the technique of reversed iliac leg stent-graft in endovascular treatment for isolated internal iliac artery (IIA) aneurysm, which had significant size discrepancy between the common iliac artery (CIA) and external iliac artery (EIA) in 3 patients from different hospitals. Three patients were a 85- and two 82-year-old men. Treated were right IIA aneurysms, sized 6.5×6.2 cm, 5.0×4.0 cm, and 4.1 cm in longest diameter, respectively. The diameters of the right CIA and right EIA measured 21 mm/11 mm, 15 mm/11 mm, and 20 mm/10 mm, respectively. In all cases, reversed iliac leg stent-grafts were prepared on-site; unsheathed and mounted upside-down manually, and deployed in each right CIA. Post-stent-graft angiograms showed complete exclusion of the aneurysms, except for minimal type 1 endoleak in one case. This technique is a useful treatment option in patients with isolated IIA aneurysm.