Abstract: Objective To explore the geno type and allele frequency of methy lene-tetrahydrofolate reductase(MTHFR) and cysta thionine beta-synthase(CBS)in women at child-bearing age in Changzhi city.Methods The genotype of MTHFR C677T was analyzed by polymerase chain reaction-restriction fragment polymorphism(PCR-RFLP),and the geno type of CBST833C and CBSG919A was detected by amplification refractory mutation system(ARMS)for 50 blood spot DNA from normal women aged 25-35 years.Results The numbers of the women with CC,TC and TT geno type of MTHFR C677T were 6,24,and 20.The frequencies of T,C and CC among the women were 36%,64%,and 40%.The numbers of the women with TT,TC and CC geno type of CBST 833C were 6,26,and 18.The frequencies of T,C and CC among the women were 38%,62%,and 36%.The numbers of women with GG,GA and AA geno type of CBSG 919A were 8,30,and 12.The frequenies of T,C and CC among the women were 46%,54%,and 24%.Conclusion The distribution of MTHFR C677T and CB ST833C geno type seems to be consistent with the development of neural tube defects in Changzhi city.The study provides genetic epidemiological data for etiological hypothesis about CBS and disease relative to folate metabolism.