e18516 Background: Neutrophil-lymphocyte ratio (NLR) is not an only inflammation marker, but also used as a prognostic index of various malignancies. Small cell lung cancer (SCLC) is considered metastatic at time of diagnosis, and survival is quite short. There is no any study evaluating the relationship between NLR and survival in SCLC. In this study, we aimed to determine the effect of NLR on overall survival. Methods: The study included 200 patients with SCLC. Survival times of patients, clinicopathological data and the results of a complete blood count at diagnosis were evaluated from patient archive files retrospectively. Patients were randomized into two groups according to NLR 5< or 5≥. Results: The median age of patients was 56 (36-80) years. One hundred and eighty one (90.5%) patients were male and 19 (9.5%) were males. Sixty-eight (34%) patients had dyspnea, 36 (18%) of cases had cough, 22 (11%) patients had back pain, and 14 (7%) of the cases had chest pain. While the duration of symptoms longer than 3 months in 90 (45%) patients, 110 (55%) patients had symptoms shorter than 3 months. Seventy-two (36%) patients had limited disease, 128 (64%) patients had extensive disease at the time of diagnosis. Twenty-one (10.5%) patients had brain metastasis initially. The median neutrophil count was 5.46 (1.02-20.2) 103 µl, and the median lymphocyte 1.69 (0.27 to 21.9) 103 µl, and median NLR was 3.19 (0.04 to 37.63) respectively. NLR overall survival rate was lowering in patients with greater than or equal to 5 group (5 ≥ group=7 months, 5< group=10 months) (p = 0.004). Conclusions: NLR is an important prognostic index that emphasis on the relationship between cancer and host in SCLC. However, a blood test is cheap and easy to use. This study was concluded that survival was shorter in patients with NLR ≥ 5 in SCLC.