Background: The purpose of this study was to analyze the predictive value of neutrophil/lymphocyte ratio (NLR) to better clarify which patient groups will benefit the most from particular treatments like bevacizumab. Materials and Methods: A total of 245 treatment-naive metastatic colorectal cancern (mCRC) patients were retrospectively enrolled and divided into 2 groups: 145 group A patients were treated with chemotherapy in combination with bevacizumab, and 100 group B patients were treated as above without bevacizumab. Results: Group A patients had better median overall survival (OS) and progression-free survival (PFS) (24.0 and 9.0 months) than group B patients (20 and 6.0 months) (p=0.033; p=0.015). In patients with low NLR, OS and PFS were significantly longer in group A patients (27 vs 18 months, p=0.001; 11 vs 7 months, p=0.017). Conclusions: We conclude that NLR, a basal cancer related inflammation marker, is associated with the resistance to bevacizumab-based treatments in mCRC patients.