Objective: To compare the pre- and post-neoadjuvant intervention chemotherapeutic expression levels of thymidylate synthase(TS),dihydropymidine dehydrogenase(DPD),thymidine phosphorylase(TP),and methylenetetrahydrofolate reductase (MTHFR),and to explore the relationship between the expression of these four genes and the neoadjuvant intervention chemotherapeutic effects. Methods: Forty-nigh patients with advanced gastric cancer were divided into neoadjuvant chemotherapeutic group (39 patients) and operative group (10 patients). The gene expression levels of TS,TP,DPD,and MTHFR in biopsy specimens from gastroscope and tumor tissue specimens after surgical resection were detected by real-time PCR. Results: According to the results of histopathology,neoadjuvant chemotherapeutic patients were divided into chemotherapeutic effective group (27 cases) and noneffective group (12 cases). The effective rate of neoadjuvant chemotherapy was 69.2%. The expression levels of four detected genes in the tumors of effective patients before neoadjuvant intervention chemotherapy were generally lower than that of the noneffective cases,and the level of DPD decreased 51.2%(P < 0.05). After neoadjuvant intervention chemotherapy,the levels of TS,TP and DPD in the effective group were 50.3%,51.3%,and 31.2% lower than those of noneffective group,respectively (all P < 0.05). The expression levels of TS and TP in effective group decreased by 38.6% and 48.7% compared with that before chemotherapy,respectively (P < 0.05),while the levels of four genes in noneffective group exhibited no significant difference between before and after chemotherapy (P > 0.05). Conclusion: The patients with low level of DPD expression in tumors before neoadjuvant chemotherapy and low levels of TS,TP,DPD after neoadjuvant chemotherapy were sensitive to the neoadjuvant intervention chemotherapy. And the decreased levels of TS and TP after neoadjuvant chemotherapy were important for evaluating the prognosis of neoadjuvant chemotherapy.