Objective To study the changes of cytokines in aqueous humor of patients with proliferative diabetic retinopathy (PDR)after intravitreal bevacizumab (IVB) and the correlation of these cytokines.Methods Fifty-six patients(63 eyes) with severe PDR underwent pars piana vitrectomy (PPV) with IVB pretreatment in our hospital from April,2014 to February,2015 were collected.All the patients received IVB therapy from 3 days to 7 days before PPV.Aqueous humor samples were collected at the time of IVB and PPV treatment.The concentrations of vascular endothelial growth factor (VEGF),interleukin-6 (IL-6),interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1) were measured by cytoinetric bead array (CBA).The changes of these cyto-kines after IVB were analyzed by using Wilcoxon rank sum test for paired data.The correlation between these cytokines was analyzed by using Spearman rank test.Results From 3 days to 7 days after IVB,the concentration of VEGF in aqueous humor was (6.57 ± 12.29)pg · mL-1,lower than the pre-operation of (278.71 ±340.20)pg · mL-1,the difference was statistically significant (P ＜ 0.05).The concentration of IL-8 was (385.60 ± 1099.47) pg · mL-1,higher than pre-operation of(298.87 ± 1005.79) pg ·mL-1,the difference was statistically significant (P ＜ 0.05).IL-6 and MCP-1 were increased after IVB,but the difference was not statistically significant (all P ＞ 0.05).VEGF,IL-6,IL-8 and MCP-1 had an obviously relationship between each two factors(all P ＜ 0.05).Conclusion Angiogenesis in patients with PDR are regulated by a variety of cytokines,and targeted reduction of VEGF may compensatory increase the concentration of other inflammatory cytokines.