Objective:To explore the risk factors related to acute rejection (AR) after pediatric kidney transplantation (KT).Methods:Retrospective analysis was performed for 189 pediatric KT recipients from September 2011 to August 2022.They were divided into two groups of AR (n=33) and non-AR (n=156).Univariate and multivariate Logistic regression analyses were performed for identifying potential risk factors of AR.And the effects of AR on graft function and survival were also examined.Results:During follow-ups, a total of 33(17.5%) patients developed AR with a 1-year cumulative incidence of AR of 16.9%(32/189).Univariate analysis revealed that median time on dialysis was longer in AR group than that in non-AR group (19 vs. 11 months, P=0.034).Median age of donors (12 vs. 24 months, P=0.033), median weight of donors (9.5 vs. 12 kg, P=0.025) and median donor/recipient body weight ratio (0.36 vs. 0.50, P=0.005) were lower in AR group than those in non-AR group.And the proportion of subtherapeutic tacrolimus (TAC) trough level was higher in AR group than that in non-AR group (45.5% vs. 21.2%, P=0.004).Multivariate regression analysis indicated that subtherapeutic TAC trough level was an independent risk factor for AR ( OR=2.977, 95% CI: 1.314-6.743, P=0.009).At the last follow-up, serum creatinine and eGFR were (78.4±24.3) vs. (74.6±24.7) μmol/L and (85.3±26.3) vs. (89.5±24.2) ml·min -1·1.73 m -2 in AR and non-AR groups respectively.There were no significant differences.1/5-year patient survival rate was both 97% in AR group and both 99.4% in non-AR group; 1/5-year graft survival rate both 90.9% in AR group and was 98.1% and 97.4% in non-AR group.No significant inter-group differences existed in patient and graft survival. Conclusions:Although an occurrence of early AR does not negatively impact graft outcomes, the incidence of AR remains high after pediatric KT.Therefore prompt diagnosis and treatment of AR should be strengthened.