Beta-blockers significantly reduce elevated factor VIII (FVIII) levels in patients with venous thromboembolism (VTE). To determine whether beta-adrenergic receptors are important in the aetiology of high FVIII levels, we investigated four coding polymorphisms of the beta1- and beta2-receptor genes in 64 patients with high FVIII and VTE and 100 healthy controls. Genotypic and allelic frequencies were not significantly different between the patient and control groups. However, a significant dosage effect of the beta2 E27 allele on plasma FVIII coagulant activity levels was observed in normal group O individuals.