AIM: To investigate the possible relationship between inflammatory biomarkers in the peripheral blood of patients with branch retinal vein occlusion (BRVO). METHODS: A total of 63 BRVO patients were enrolled in this cross-sectional observational study. Meanwhile, 63 age- and gender-matched cataract patients were included as controls. Complete blood count and biochemical tests were performed, and inflammatory biomarkers including platelet to lymphocyte ratio (PLR), red blood cell distribution width to albumin ratio (RAR), neutrophil to lymphocyte ratio (NLR), systemic immune inflammation index (SII), and monocyte to high density lipoprotein cholesterol ratio (MHR) were compared between the two groups. RESULTS: There were no significant differences between the two groups in terms of age, sex, and prevalence of diabetes mellitus. Compared with the controls, patients with BRVO had a higher prevalence of hypertension and higher body mass index (BMI). Red blood cell distribution width (RDW), triglycerides, MHR, NLR, and RAR were elevated, whereas lymphocyte count and high-density lipoprotein were decreased in the BRVO group. Multivariate logistic regression analysis revealed that NLR (adjusted OR=1.686, 95%CI 1.075-2.646), RAR (adjusted OR=8.930, 95%CI 1.911-41.730), and body mass index (BMI; adjusted OR=1.174, 95%CI 1.010-1.365) were significantly associated with the risk of BRVO. In the receiver operating characteristic analysis, the area under the curve for NLR, RAR, and BMI were 0.602, 0.630, and 0.603, respectively. The sensitivity and specificity were 61.9% and 60.3%, 38.1% and 82.5%, and 61.9% and 57.1%, respectively. CONCLUSION: Peripheral blood inflammatory biomarkers are elevated in BRVO patients, suggesting systemic inflammation involvement. NLR, RAR, and BMI are positively correlated with BRVO. Monitoring NLR and RAR and strict weight control may be beneficial for the prevention and treatment of BRVO.