ABSTRACT: The prognostic role of the neutrophil-to-lymphocyte ratio (NLR) has been reported in colorectal cancer (CRC); however, its variation and corresponding predicative value in patients undergoing resection remain largely unknown. In the present study, data from 146 patients with CRC were retrospectively collected, optimal cut-off points for preoperative and postoperative low and high NLRs were set, and ?NLR was calculated. Subsequently, patients were classified into low-low, low-high, high-low and high-high subgroups based on the cut-off points, and their progression-free survival (PFS) was determined. A Cox proportional hazard model was applied to calculate the prognostic value of all factors. The results demonstrated that both preoperative and postoperative NLRs (pre-NLR and post-NLR) but not ?NLR could predict PFS with optimal cut-off points of 2.39 and 2.96, respectively. For predicting PFS, the pre-NLR had a sensitivity and specificity of 48.80 and 79.50%, respectively, and the post-NLR had a sensitivity and specificity of 63.20 and 56.20%, respectively. Significant differences were identified between low and high pre-NLRs in terms of histological grade (P<0.01) and tumor diameter (P<0.01); however, such differences were only found in terms of age (P<0.01) for low and high post-NLRs. The PFS of patients in the low-low, low-high, high-low and high-high subgroups was 50.30±21.36, 43.67±22.78, 31.06±25.56 and 29.87±24.13 months, respectively, and patients in the high-high subgroup had the worst PFS (P<0.01). Preoperative CEA level, invasive depth, node involvement, distant metastasis and preoperative NLR were independent prognostic factors. In conclusion, a persistently high NLR for patients with CRC undergoing resection was associated with poor prognosis.