Objective To observe the levels of vascular endothelial growth factor (VEGF), interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1) in aqueous humor of patients with macular edema secondary to central retinal vein occlusion (CRVO). Methods Forty eyes of 40 consecutive patients with macular edema secondary to CRVO (CRVO group) were enrolled in this study. The patients included 25 males and 15 females. The patient age ranged from 38 to 76 years. The control group was 20 patients with senile cataract who underwent phacoemulsification, including 10 males and 10 females. The levels of VEGF165, VEGF165b, IL-6 and MCP-1 in aqueous humor were determined by enzymelinked immunosorbent assay. The correlation of VEGF, and IL-6, and MCP-1 were analyzed. Results The median aqueous level of VEGF165, IL-6 and MCP-1 were 1089.0, 165.6, 1253.0 pg/ml respectively in CRVO group, which were higher than the control group's results (168.2, 4.7, 216.4 pg/ml respectively), the differences were statistically significant (Z=-4.549, -6.008, -5.343;P＜0.001). The VEGF165b in CRVO group and control group were 834.0, 915.9 pg/ml respectively, the difference was not statistically significant (Z=-0.207，P＞0.05). The ratio of VEGF165b to VEGF165 in CRVO group and control group were 2.71, 7.28 respectively, the difference was statistically significant (t=-3.007，P＜0.05). There was a highly positive correlation between IL-6 and VEGF in CRVO group (r=0.526,P=0.001) and also mild positive correlation in control group (r=0.425，P=0.070). No correlation between MCP-1 and VEGF was observed in both groups (CRVO group: r=0.211,P＞0.05. Control group: r=-0.019,P＞0.05). Conclusions VEGF165, IL-6 and MCP-1 levels were increased in CRVO patients while the VEGF165b was normal. The ratio between VEGF165b and VEGF165 in aqueous humor of patients with macular edema secondary to CRVO was decreased.