This paper describes the relationship of factor VII coagulant activity (FVIIc), FVII Arg/Gln353 genotype and risk of myocardial infarction (MI) in the ECTIM (Etude Cas Témoin sur l'Infarctus du Myocarde) study, a multi-centre case-control study on MI. FVIIc was significantly higher in controls from all four centres: Belfast, Lille, Strasbourg and Toulouse, perhaps because elevated FVIIc may predispose to fatal rather than non-fatal MI. Major influences on FVIIc were FVII Arg/Gln353 genotype, triglyceride and cholesterol levels. There was no significant effect of genotype on MI risk however there was a non-significant trend towards increased MI risk in FVII Arg353 homozygotes. Confirming previous observations, FVIIc was highest in FVII Arg353 homozygotes, intermediate in heterozygotes and lowest in FVII Gln353 homozygotes (except Toulouse cases) these differences being highly statistically significant (except Strasbourg cases P = 0.1). In Belfast, consistent with previous findings, there was significant interaction between FVII Arg/Gln353 genotype and triglyceride level in determining FVIIc, whilst this was absent in the French centres. In conclusion, FVII Arg/Gln353 genotype strongly determines FVIIc although neither factor has a strong impact on MI risk in the ECTIM study.