Plain Language SummaryWith advancements in therapies reducing the risk of graft-associated complications after kidney transplantation (KT), our focus shifts toward ensuring optimal graft conditions to improve the quality of life for KT patients. This emphasizes the importance of identifying prognostic factors of kidney function, even in populations without graft-associated complications. Oxidative stress, which is characterized by an imbalance in the production and neutralization of free radicals in the body, has been linked to graft-associated complications. Moreover, a significant determinant of graft function is the source of the graft, whether obtained from living donation (LD) or donation after circulatory or brain death (DCD and DBD). Therefore, we aimed to study whether oxidative stress differed in the short-term after KT in patients receiving LD, DCD, and DBD, and whether these levels of oxidative stress were predictive of graft function in KT patients without long-term complications such as rejection. We examined oxidative stress in 41 KT recipients over 12 months, finding increased oxidative damage early post-KT, notably higher in DCD donors. Moreover, lower oxidative damage in the first week after KT predicted better 1-year graft function in DBD recipients. In conclusion, DCD induced more short-term oxidative damage, while early oxidative levels predicted 1-year graft function in DBD recipients. These findings underscore the importance of early oxidative stress assessment in guiding clinical decision-making and optimizing long-term outcomes in KT recipients.