Controversies exist regarding the impact of obesity on patients undergoing kidney transplantation. We sought to estimate the association between BMI and patient outcomes (survival and graft function) among pediatric kidney transplant patients in the USA. We conducted a retrospective analysis of the United Network for Organ Sharing database (1987-2013), which revealed 13 014 pediatric patients (<18 years old) who underwent primary kidney transplantation. Patients were stratified into five BMI categories established by the World Health Organizations according to their Z score, which is based on age, gender and BMI. The -2, 0, and +2 categories were collapsed and served as the reference group, while the -3 (thin) and +3 (obese) categories were evaluated for differences in graft and patient survival. The survival rates between these categories were compared using the Kaplan-Meier estimator. Cox proportional hazards models were constructed to adjust for recipient and donor characteristics to estimate the risk of graft loss and mortality associated with BMI. Logistic regression models were estimated to evaluate whether there was an association between BMI and DGF. There were no differences in overall patient (P=.1655) or graft (P=.1688) survival between the severely thin, normal, and obese patients. Adjusted models also revealed no statistically significant differences in graft or patient survival. There were no differences in the odds of DGF (both unadjusted and adjusted) among the three groups. The prevalence of obesity is increasing among children who present for kidney transplant in the USA. In this national study of pediatric kidney transplant recipients, there was no difference in graft or patient survival and no differences in rates of DGF among obese children compared to normal and underweight children undergoing kidney transplantation.