['We investigated the relationship between NOS3, FGB and PAI-1 polymorphisms and endothelial dysfunction and risk factors for acute myocardial infarction (AMI) in young adults.', 'Endothelial function was measured by response to flow mediated vasodilation (FMV) and induced by nitrate (FMN). Biochemical parameters were measured by standard enzymatic methods and plasma total nitrate was analyzed by the NOA system. NOS3 (T-786C, G894T and intron 4A/B STR), FGB (C-148T and G-455A) and PAI-1 (4G/5G) polymorphisms were determined by PCR-RFLP.', 'Concentrations of total and LDL cholesterol, apo B, triglycerides, nitrate, PAI-1 and fibrinogen were higher and apo AI, HDL cholesterol and FMV were lower in AMI patients than in controls (p<0.001). PAI-1 (p<0.001) but not nitrate was higher in AMI patients with low response to FMV. NOS3 T-786C and FGB C-148T polymorphisms were associated with AMI (p<0.050). NOS3 T-786C was also related to hypertension (p=0.049). NOS3 intron 4A/B STR was associated with increased concentrations of total cholesterol and apo B. NOS3-786TT/894GT haplotype was associated with increased FMV (p=0.018) than the other haplotypes.'] Is aMI associated with polymorphisms in the NOS3 and FGB but not in PAI-1 genes in young adults?