Background: Community acquired pneumonia is one of the most common infectious disease, and is an important cause of morbidity and mortality among the elderly worldwide Present study aimed to investigate the usefulness of Neutrophil Lymphocyte Ratio (NLR) as a biomarker of Community Acquired Pneumonia (CAP) Material & Method: Present diagnostic comparative study was conducted among the patients more than 18yr of age with community acquired pneumonia, attending department of General Medicine of AVMC & H. After obtaining informed and written consent from the patients, detailed history, clinical assessments and laboratory investigations was done. The NLR ratio, CURB 65 score and PSI calculated and compared. All data were collected by the investigator and was analysed statistically to find the level of significance of the study. Results: Two hundred and four patients included with mean age of 57.11±16.35yrs of age. Among them, 60.3% were male patients and 39.7% were female. On comparison of the scores with 1st mild risk group, 2nd moderate risk group and 3rd severe risk group, we found a significant difference in the mean, with the 3 rd risk group the mean levels were significantly higher compared to group 2 and group 1.(p<0.05) On pearson’s correlation the NLR was significantly positively correlated with CURB 65 score and PSI score in the present study.(p<0.05) On ROC analysis, the study found the AUC of 0.902 for NLR, 0.922 for CURB 65 score and 0.931 for PSI score.(p<0.05)