Background: Although many prognostic factors have been identified for lung cancers, new ones are needed to determine the course of the disease. Recently, a high neutrophil to lymphocyte ratio (NLR) prior to surgery or treatment has been shown to be an indicator of prognosis for cancer. The aim of this study was to investigate the value of NLR as a prognostic factor and the correlation between NLR and other probable clinical prognostic factors in non small cell lung cancer patients prior to treatment. Materials and Methods: Data of patients who were diagnosed with non-small cell lung cancer in our institution were retrospectively reviewed. Demographic and clinicopathologic characteristics were recorded. NLR was calculated before the application of any treatment. Results: A total of 299 patients, 270 (90%) males and 29 (10%) females, were included in the study. Age (p<0.001) stage (p<0.001), Eastern Cooperative Oncology Group performance status (p<0.001), weight loss (p<0.001), anemia (p<0.001), histopatology (p<0.001), NLR >= 3 (p=0.048), NLR >= 4 (p=0.025) and NLR >= 5 (p=0.018) were found to be the prognostic factors. Age, anemia, Eastern Cooperative Oncology Group performance status, the stage, NLR (>= 5) were an independent prognostic factors. There was a positive correlation between NLR and the Eastern Cooperative Oncology Group performance status (0.23, p=0.001), the C reactive protein levels (r=0.36, p<0.001). Conclusions: Prior to treatment high NLR was found as an independent poor prognosis factor. Besides, NLR correlated with Eastern Cooperative Oncology Group performance status and the C reactive protein levels.