BACKGROUND The aim of our study was to evaluate all lesions in the adenoma-dysplasia-cancer sequence of the colon and to examine whether the neutrophil-to-lymphocyte ratio (NLR) can distinguish polyps indicating dysplasia and cancer. MATERIAL AND METHODS A total of 397 patients who had colonoscopic polypectomy between January 2010 and December 2014 were included in our retrospective study. The patients were divided into four groups: patients with hyperplastic polyps, patients with adenomatous polyps, patients with dysplasia, and patients with cancer. The NLR was calculated as a simple ratio indicating the relationship between counts of absolute neutrophil and absolute lymphocyte. RESULTS The NLR increased in line with the adenomatous polyp-dysplasia-cancer sequence, with the highest ratio established among cancer patients (2.05 (0.27-10), 2.34 (0.83-14.70) and 3.25 (0.81-10.0), respectively). The NLR was significantly higher among cancer patients than among patients with adenomatous polyps and hyperplastic polyps (p values were 0.001 and 0.004, respectively). The lymphocyte count of cancer patients was prominently lower when compared to those in groups with adenomatous polyps and hyperplastic polyps (p values were 0.001 and 0.003, respectively). The NLR was found to be significantly higher in patients with polyps larger than 10 mm [2.71 (0.90-14.70)] when compared to those with polyps smaller than 10 mm [2.28 (0.27-11.67)] (p<0.001). With the NLR threshold set at 2.20, it was possible to predict cancerous polyps with a sensitivity of 71.4% and a specificity of 52.5% (AUC: 0.665, 95% CI: 0.559-0.772, p=0.001). CONCLUSIONS NLR is a cheap, universally available, simple and reliable test that can help predict cancerous polyps. It can be used as a non-invasive test for monitoring polyps.