Patients with end-stage renal disease (ESRD) who receive dialysis have been shown to have impaired neuropsychological performance. It remains unclear, however, whether cognitive deficits associated with ESRD and/or dialysis are reversible after successful kidney transplantation. Thus, the main purpose of this study was to longitudinally compare the cognitive performance of adequately dialyzed patients with ESRD before and shortly after kidney transplantation. Twenty-two dialyzed patients with ESRD who subsequently received a kidney transplant, 20 dialyzed patients who were medically qualified and awaiting kidney transplant but did not receive it, and 30 matched controls were the participants for this study. Overall, our results demonstrate that a successful kidney transplant is associated with improved neuropsychological performance in patients with ESRD. Specifically, a significant improvement was seen on measures of psychomotor speed, visual planning, retrieval of learnt material, and abstract thinking. Additionally, the degree of cognitive improvement following kidney transplant was significantly associated with some pre-, intra-, and postoperative factors (e.g., age, duration of chronic kidney disease, postoperative graft function). The results of this study also show that the cognitive performance of adequately dialyzed patients without a kidney transplant, although often below that of matched controls, remains relatively stable over time.