Several recent studies have reported contradicting results concerning the relevance of the plasminogen activator inhibitor-1 (PAI-1) 4G/5G-polymorphism for myocardial infarction. In addition, the common factor V Q506 (FV:Q506) mutation is frequently discussed as a risk factor for arterial thrombosis, but evidence is rare. In order to further highlight the role of both polymorphisms in myocardial infarction, we investigated 241 young male myocardial infarction patients (≤ 45 years-of-age) aged 38.6 ± 4.4 years (mean ± SD) for the presence of both genotypes. The control group consisted of 179 healthy men aged 47.1 ± 6.4 years (mean ± SD) of the same ethnic background as the patients. Neither the distribution of the PAI-1 4G/5G-polymorphism nor the prevalence of the FV:Q506 mutation was significantly different between young patients and controls (4G/4G-genotype:x2= 2.08, NS; odds ratio 1.36, 95% confidence interval 0.89–2.06; FV:Q506 mutation:x2= 0.33, NS; odds ratio 1.33, 95% confidence interval 0.64–2.78). Moreover, the PAI-1 4G/5G-distribution did not differ significantly between patients and controls in subgroups by tertiles of triglyceride levels. In conclusion, in the present study neither homozygosity for the 4G allele of the PAI-1 4G/5G-polymorphism nor the FV:Q506 mutation led to an increased risk of myocardial infarction in young men.