Background: Early VEGF-A reduction by targeting abundant VEGF-A is a potential predictive marker of bevacizumab (BV). CCL5/CCR5 axis modulates VEGF-A production via endothelial progenitor cells migration. We tested whether genetic polymorphisms in CCL5/CCR5 pathway will predict outcomes in metastatic colorectal cancer (mCRC) patients (pts) receiving BV in first-line setting. Methods: Genomic DNA was extracted from 215 samples of three independent cohorts: 61 pts receiving FOLFOX+BV (median age 60 yrs, median follow-up 39.2 mos); 83 pts receiving FOLFOX (median age 61 yrs, median follow-up 57.6 mos); 71 pts receiving FOLFOX/XELOX+BV as exploratory for serum biochemistry assay (median age 60 yrs, median follow-up 28.9 mos). Single nucleotide polymorphisms of genes in CCL5/CCR5 pathway were analyzed by PCR-based direct sequencing. Serum VEGF-A levels at baseline and day 14 were measured using ELISA. Results: In univariate analysis for the FOLFOX cohort, pts with the CCL5 rs2280789 G/G variant or any CCR5 rs1799988 T allele had shorter overall survival (OS) compared to the those with any A allele or the C/C variant (18.7 vs. 29.4 mos, HR 1.93, 95%CI: 1.05−3.53 P= 0.025; 22.0 vs. 31.2 mos, HR 1.74, 95%CI: 0.98-3.90, P= 0.055). The trend remained in multivariable analysis (P= 0.090 and P= 0.026). The differences were not confirmed in the FOLFOX+BV cohort. Pts with any CCL5 rs2280789 G allele had longer progression-free survival (PFS) and OS when receiving FOLFOX+BV than FOLFOX (PFS: 19.8 vs. 11.0 mos, HR: 0.44, 95%CI: 0.25-0.78, P= 0.002; OS: 41.8 vs. 21.1 mos, HR: 0.43, 95%CI: 0.24-0.77, P= 0.002); pts carrying any CCR5 rs1799988 T allele had longer PFS and OS (P= 0.025 and P= 0.008, respectively). No significant difference was shown in pts with either A/A or C/C variant. In the exploratory cohort, any CCL5 rs2280789 G allele was associated with higher VEGF-A levels at baseline and greater decrease of VEGF-A levels at day 14 compared with the A/A variant. Conclusions: CCL5 and CCR5 impact the angiogenic environment. Our data suggest the genotypes may identify specific populations who benefit from BV-based chemotherapy in first-line treatment for mCRC.