The role of elevated post-Transplant red cell distribution width (RDW) as a predictive factor for graft loss remains unclear, although RDW was reported to be significantly associated with poor prognosis in various clinical fields. We performed a retrospective cohort study with 2,939 kidney transplant patients from two tertiary teaching hospitals in Korea. RDW level at transplantation and 3-months post-Transplantation were collected. Those with RDW in the upper quartile range were considered to have increased RDW (>14.9%). Death-with-graft-function (DWGF), death-censored graft failure (DCGF), and composite graft loss were assessed as the study outcomes, using multivariable cox proportional hazard model. At the median follow-up duration of 6.6 (3.6-11.4) years, 336 patients experienced graft loss. There were 679 patients with elevated RDW at 3-months post-Transplant. Elevated RDW was associated with composite graft loss (adjusted hazard ratio, 1.60, 95% confidence interval, 1.23-2.07, P < 0.001), even after adjusted for hemoglobin and various clinical factors. The 1% increment of post-Transplant RDW was also significantly associated with the outcome, regardless of the presence of anemia. The worst prognosis was seen in patients with elevated RDW after transplantation, but not at baseline. Therefore, post-Transplant RDW level may be significantly associated with patient prognosis, independent of hemoglobin values.