Aim To study the relationship of polymorphisms of methylenetetrahydrofolate (MTHFR) gene and plasma homcysteine (Hcy) levels with myocardial infarction. Methods 178 myocardial infarction patients and 178 normal subjects were recruited in the study. Their polymorphisms of MTHFR gene were analyzed using PCR RFLP and their plasma total Hcy levels were measured using high performance liquid chromatography with fluorescence detection. Results There were three kinds of genotype: TT (homozygous mutation), TC (heterozygous mutation) and CC (wild type). The frequencies of the three genotypes were as follows: TT, 35.4%; TC, 53.8%; CC, 10.8% in myocardial infarction patients and TT, 20.1%; TC 55.8%; CC, 24.1% in normal subjects, respectively. The frequency of T alleles was significantly higher in myocardial infarction patients than that in normal controls (62.3% and 37.7%, respectively). Mean total plasma homocysteine concentrations were significantly higher in myocardial infarction patients than in the normal subjects. Conclusions These results suggest that polymorphisms of MTHFR gene and hyperhomocysteinemia may be an independent risk factor for myocardial infarction.