Objective To explore the diagnostic value of serum EphA5 gene promoter methylation in prostate cancer(PCa).Methods A total of 71 PCa patients admitted to Affiliated Hospital of Xuzhou Medical University from June 2022 to June 2023 were selected as the study subjects,with 49 patients with benign prostatic hyperplasia(BPH)and 20 healthy individuals during the same period as the control groups.The methylation-specific polymerase chain reaction(MSP)technology was used to detect the methylation status of serum EphA5 gene promoter in all study subjects.The relationships between EphA5 gene promoter methylation and clinic pathological parameters were evaluated by the chi-square test.The receiver operating characteristic(ROC)curve was drawn and used to analyze the diagnostic value of combined detection of EphA5 gene promoter methylation and prostate specific antigen(PSA)in PCa.Results The results of MSP showed that the methylation rate(84.5%,60/71)of serum EphA5 gene promoter in PCa patients was significantly higher than those in BPH patients(24.49%,12/49,P＜0.05)and healthy controls(15%,3/20,P＜0.05).The methylation rate of serum EphA5 gene promoter in PCa patients was correlated with TNM staging(P＜0.05)and Gleason score(P＜0.05).The areas under the ROC curve(AUCROC)of PSA and EphA5 gene promoter methylation in the diagnosis of PCa were 0.868(95%CI:0.810-0.925)and 0.800(95%CI:0.723-0.878),respectively.The AUCROC of the combined detection of PSA and EphA5 gene promoter methylation in the diagnosis of PCa could be raised to 0.901(95%CI:0.853-0.950),and its diagnostic efficiency was better than the single detection of each indicator.Conclusion The methylation level of serum EphA5 gene promoter in PCa patients is significantly higher than those in BPH patients and healthy controls,indicating that serum EphA5 gene promoter methylation may serve as a potential biomarker of PCa.