Objective: Branch retinal vein occlusion (BRVO) is a common cause of severe visual loss. Numerous risk factors, including arterial hypertension, diabetes mellitus, and arteriosclerosis, have been identified. Gene polymorphisms affecting hemostasismay also play a role in the pathogenesis of BRVO. The present study was therefore done to determine the prevalence of genetic polymorphisms in factors implicated in hypercoagulability among patients with BRVO. Design: Retrospective case-control study. The study cohort consisted of 294 patients with BRVO and 294 control subjects, matched for age and gender. Methods: Determination of genotypes was done by allele-specific digestion of polymerase chain reaction product s, or by 5 exonuclease assay (TaqMan). Main Outcome Parameters: Genotypes of factor V R506Q (factor V Leiden), prothrombin 20210G>A, fibrinogen β-455G> A, factor XII (FXII) 46C>T, and ITGA2 807C>T (platelet glycoprotein Ia GPa 807C > T) and ITGB3 L59P (platelet GPIIIa PlA1/PlA2) polymorphisms. Results: Genotype distributions of the investigated gene polymorphisms did not differ significantly between patients and control subjects. In contrast, significantly increased prevalences of arterial hyper-tension and hypercholesterolemia were found among patients with BRVO. In a logistic regression analysis, the presence of arterial hypertension was associated with an odds ratio (OR) of 2.32 (95%confidence interval CI, 1.62-3.32),whereas hypercholesterolemia yielded an OR of 2.54 (95%CI, 1.74-3.70) for BRVO. Conclusion: Our data indicate that the prevalences of the investigated gene polymorphisms do not differ significantly in patients with BRVO and control subjects. This suggests that these polymorphisms are not major risk factors for BRVO. Objective: Branch retinal vein occlusion (BRVO) is a common cause of severe visual loss. Numerous risk factors, including arterial hypertension, diabetes mellitus, and arteriosclerosis, have been identified. Gene polymorphisms affecting hemostasismay also play a role in the pathogenesis of BRVO. The present study was therefore done to determine the prevalence of genetic polymorphisms in factors implicated in hypercoagulability among patients with BRVO. Design: Retrospective case-control study. The study cohort consisted of 294 patients with BRVO and 294 control subjects, matched for age and gender . Methods: Determination of genotypes was done by allele-specific digestion of polymerase chain reaction product s, or by 5 exonuclease assay (TaqMan). Main Outcome Parameters: Genotypes of factor V R506Q (factor V Leiden), prothrombin 20210G> A, fibrinogen β-455G> A, factor XII (FXII) 46C> T, and ITGA2 807C> T (platelet glycoprotein Ia GPa 807C> T) and ITGB3 L59P (platelet GPIIIa PlA1 / PlA2) po Results: Genotype distributions of the investigated gene polymorphisms did not differ significantly between patients and control subjects. In contrast, significantly increased prevalences of arterial hyper-tension and hypercholesterolemia were found among patients with BRVO. In a logistic regression analysis, the presence of arterial hypertension was associated with an odds ratio (OR) of 2.32 (95% confidence interval CI, 1.62-3.32), whereas hypercholesterolemia yielded an OR of 2.54 (95% CI, 1.74-3.70) for BRVO. the prevalences of the investigated gene polymorphisms do not differ significantly in patients with BRVO and control subjects. This suggests that these polymorphisms are not major risk factors for BRVO.