Objective To elucidate the association of plasma factor Ⅷ oagulant activity(FⅦc)with me risk of myocardial infarction (MI) and to assess the influence of factor Ⅶ gene Mspl polymorphism and lipid metabolism on FⅦc in the Chinese. Methods A total of 137 patients with angiographically confirmed MI and 125 healthy individuals were evaluated retrospectively. Plasma FⅦC was measured by one-stage prothrombin time,and FⅦ genotype was determined after Mspl digestion of polymerase chain reaction-amplified genomic DNA.Serum lipidlevels were assessed by routine methods.Results MI patients had significantly higher levels of FⅦc (119.5%±22.7% vs 99.9%±21.8%,P＜0.01) and total serum cholesterol (5.80±1.06mmol/L vs 5.53±1.08 mmol/L, P＜0.05) than controls, but only FⅦc independently correlated with the risk of MI (OR=1.04, P＜0.01). There were no significant differences in FⅦ genotype or allele frequency between patients and controls (P＞0.05).Subjects with the Gln353 allele were associated with significantly lower FⅦc levels than Arg353homozygotes (99.7%±19.3% vs 111.4%±24.6%,P＜0.05). Serum triglyceride was positively correlated with plasma FⅦc in both control(r=0.25, P＜0.01)and case (r=0.87, P＜0.01) groups, but this correlation was restricted to Arg/Arg genotypa (r=0.68, P＜0.01).A significant correlation of total serum cholesterol with FⅦc only appeared in Arg/Arg homozygotes (r=0.17, P＜0.01). Conclusions Our findings support the role of plasma FⅦc as a risk factor for MI in Chinese. Plasma triglyceride and FⅦ gene Mspl pclymorphism are two independent determinants of FⅦc. Assay of this polymorphism will be helpful in determining who will benefit most from lipid-lowing therapy.