The odds ratio of homozygosity or heterozygosity for the TNF2 polymorphism in 575 patients with venous thromboembolism compared to controls was found to be 1.0 (95% CI 0.4-2.1) and 1.1 (95% CI 0.8-1.4) respectively. Comparing subgroups of patients and controls with the factor V Leiden mutation the odds ratio for the TNF2 polymorphism was 0.7 (95% CI 0.2-2.2). Despite evidence of a link between high tumour necrosis factor (TNF) levels and hypercoagulability, our results do not indicate a link between the genetic regulation of TNF production and venous thromboembolic disease.