Objective: In this study, we aimed to reveal the level of predicting mortality of the Neutrophil/Lymphocyte (NLR) and Platelet/Lymphocyte Ratios (TLR) calculated in patients hospitalized with the diagnosis of pneumonia in the intensive care unit when compared with other prognostic scores. Method: The hospital records of 112 patients who were admitted to the intensive care unit between January 2015 and January 2018 and met the inclusion criteria were retrospectively reviewed. The patients’ demographic data, the NLR and PLR levels, and the APACHE II (Acute Physiology and Chronic Health Evaluation II) and SOFA (Sequential Organ Failure Assessment) scores were calculated from the patient files. Results: Of the 112 patients examined, 70 were males. The risk analysis showed that the male gender had 2.7 times higher risk of mortality. The NLR, PLR, APACHE II, and SOFA values were found statistically significant in predicting mortality (p<0.001). An evaluation of the risk ratios demonstrated that each one point increase in the NLR increased the mortality risk by 5%, and each one point increase in the SOFA score increased the mortality risk by 13% (p<0.05). In the ROC (receiver operating characteristic) analysis, the NLR assessment proved to be the most powerful, most specific, and sensitive test. The cut-off values were 11.3 for the NLR, 227 for the PLR, 29.8 for the APACHE II scores, and 5.5 for the SOFA scores. Conclusion: We believe that NLR and PLR are strong and independent predictors of mortality that can be easily and cost-effectively tested.