ObjectiveTo investigate the distribution of thethymidylate synthase (TS) gene polymorphisms inChinese femaleHan-nationality breast cancer patients,including tandemrepeat polymorphisms in the enhancer region ( ER), 6 bp deletion/insertion (del6/ins6) polymorphism in the 3′untranslated region (3′-UTR) and G→C single-nucleotide polymorphism (SNP). The association of TS gene polymorphism with pathological results was retrospectively analyzed.MethodsThis study included 83 breast cancer patients who received no preoperative chemotherapy. The polymorphisms of TS, ER and TS 3′2UTR were determined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method.Results ( 1 ) Of the 83 patients, the frequencies of the TSER 3R/3 R, 2R/3 R and 2R/2R were 68.7％ ,27. 7％ and 3. 6％, respectively; (2) Due to existence of the G→C single nucleotide polymorphism,TSER genotypes were divided into 2R/2R, 2R/3C, 2R/3G, 3G/3G,3C/3C and 3G/3C,their frequencies were 3. 6％, 19. 3％, 8.4％, 19. 3％, 37. 3％ and 12. 1％, respectively; ( 3 ) Of the 83 patients, the frequencies of the TS 3′-UTR ins6/ias6、ins6/del6 and del6/del6 were 8.4％ 、50.6％ and 41.0％, respectively; (4) TSER polymorphisms were correlated with lymph node metastasis ( P = 0.019 ),Ki67 ( P = 0.022 ) and histological grade ( P = 0.042 ). The TS 3′-UTR polymorphisms were correlated with age ( P = 0.002) and histological grade (P = 0.042). G→C SNP were correlated with lymph node metastasis ( P = 0.021 ) and histological grade ( P = 0.028 ).ConclusionsChinese female Han-nationality breast cancer patients have more genotypes frequencies of the TSER 3R/3R and 3′-UTR del6/del6; The TS polymorphisms are correlated with pathological factors of breast cancer.