Previous studies of the safety of renal autotransplantation (RAT) have been limited by a lack of evidence. Because of the influence of the opposite kidney, it is difficult to evaluate actual renal function. This study evaluated the actual results of RAT by collecting only cases involving a solitary kidney.Between September 1, 1999, and November 30, 2015, 9 RAT procedures were performed in 9 patients with a solitary kidney. We retrospectively evaluated medical data collected prospectively. Renal function was evaluated using the creatinine level and the estimated glomerular filtration rate (eGFR).The indications for RAT differed among the nin9e study patients. Five patients had complex renovascular problems, 2 were treated for partial nephrectomy, 1 was had a radically resected ureter due to ureteral cancer, 1 patient underwent RAT for the preservation of renal function during suprarenal-type abdominal aortic aneurysm repair. The mean cold ischemic time was 116.66 minutes (range, 21-256), and the mean follow-up duration was 54.2 months (range, 1 to 184). There were no significant decreases in eGFR until 12 months except 1 patient who underwent RAT with partial nephrectomy due to renal cell cancer.We report stable renal function after RAT in patients with solitary kidney. Postoperative complications were rare. This is evidence for the safety of RAT.