Objective To investigate the predictive value of serum 25-hydroxyvitamin D[25(OH)D]level in early renal transplantation for acute rejection(AR).Methods A total of 324 renal transplant recipients from January 2019 to August 2022 in the Second People's Hospital of Shanxi Province were selected.The clinical data of the recipients were collected.The levels of serum 25(OH)D,parathyroid hormone(PTH),and calcium,phosphorus in early(within 1 month)transplantation were detected by chemiluminescence immunoassay and colorimetry,respectively.The detection season was recorded,and the occurrence of AR within 1 year after renal transplantation was observed.The 25(OH)D level ≥ 20ng/ml was defined as normal,≥ 12 ng/ml～＜20 ng/ml as insufficient and＜12ng/ml as deficient,they were divided into of 25(OH)D normal group(n=106),insufficient group(n=112)and deficient group(n=106).According to the occurrence of AR,they were divided into AR group(n=51)and non-AR group(n=273).The basic situation of serum 25(OH)D level was analyzed.The differences in serum PTH,calcium,phosphorus levels and seasons as well as AR incidence among the three groups of 25(OH)D were compared.Multivariate logistic regression was used to analyze the influencing factors of AR,and receiver operating characteristic(ROC)curve was used to analyze the predictive value of serum 25(OH)D level for AR.Results The incidence of serum 25(OH)D deficiency or insufficiency was 67.28％(218/324).In the 25(OH)D normal group,insufficient group and deficiency group,the serum PTH levels were 75.44(46.42,113.23)pg/ml,78.29(58.27,152.10)pg/ml and 86.84(54.64,127.3)pg/ml,and the incidences of AR were 2.47％(8/324),6.17％(20/324)and 7.10％(23/324),respectively.All of them were the highest in the deficiency group and the lowest in the normal group,and the differences were significant(H=6.784,x2=8.580,all P＜0.05).Additionally,25(OH)D deficiency(OR=3.340,95％CI:1.409～7.916),25(OH)D insufficiency(OR=2.442,95％CI:1.006～5.925)and human leucocyte antigen(HLA)mismatch(4～6)(OR=2.117,95％CI:1.027～4.363)were independent risk factors for AR(all P＜0.05).The area under the curve(AUC)of serum 25(OH)D level in predicting AR was 0.702(95％CI:0.625～0.779),the optimal cut-off value was 13.59 ng/ml,the specificity and the sensitivity were 66.7％and 65.6％,respectively.Conclusion In this study,25(OH)D deficiency(＜12ng/ml)or insufficiency(≥ 12～＜20ng/ml)was an independent risk factor for AR,and serum 25(OH)D level may have a certain predictive value for AR.