Background Although the role of fibrinogen as a predictor of acute myocardial infarction(MI)has been well-established,the association of genetic polymorphisms in the fibrinogen gene with MI is still controversial.This study was conducted to elucidate the association between the genetic polymorphisms of the fibrinogen β-chain(FGB)gene and MI in Chinese Han population.Methods The occurrence of 3 common polymorphisms(i.e.-455G/A,R448K and 8558C/G)in a case-control study including 508 patients with MI and 503 healthy controls was investigated. Results Analyses of single polymorphisms showed that individuals carrying the rare alleles for the 3 polymorphisms were significantly associated with a decreased risk of MI.Logistic regression analysis indicated that R448K remained independently associated with MI after adjustment for environmental risk factors(adjusted odds ratio(OR)=0.71 for KK/RK versus RR.P=0.023).The three polymorphisms were found to be in strong linkage disequilibrium.Haplotype analyses showed that the A-K-G haplotype(-455A,448K,8558G)was associated with a protective effect against MI.Compared with the common haplotype G-R-C,the adjusted OR for A-K-G was 0.68(95% CI,0.51-0.90;P=0.006). Conclusion These data indicate that individuals carrying the FGB 448K allele may be protective against having MI in this population.