Chronic obstructive pulmonary disease (COPD) is one of the major causes of chronic morbidity and mortality and one of the major public health problems worldwide that affects millions of people all over the world. It is characterized by persistent airflow obstruction associated with enhanced inflammation in the airways and the lungs in response to noxious particles or gases. The main objective of this study is to investigate the neutrophil-lymphocyte ratio in patients with COPD as a case-control study. Between November 01, 2022, and February 28, 2023, patients were admitted to Al Hussain Teaching Hospital in Al Muthanna Governorate, Department of Medicine. The study included 51 patients with an approved diagnosis of COPD the mean age was 51.5 years, and 51 patients as control with other diseases mean age was 51.3 years). The subjects in all groups were 32 male and 19 female. Complete blood count (CBC) was measured from blood samples taken from patients. In the present study 51 COPD cases and 51 controls. No significant difference was observed between COPD cases and controls regarding age (p = 0.092); the average age of COPD cases was 51.5 years. No significant differences were observed between COPD cases and controls regarding gender (p = 0.085). At baseline, 21.0%, 40.3%, 25.7%, and 13% were diagnosed as COPD grade 1, 2, 3, and 4, respectively based on the (GOLD) classification. Baseline NLR significantly increased with the severity of COPD grade (1.3 vs. 2.7 vs. 2.2 vs. 2.9), p = 0.002). The cutoff for neutrophil-to-lymphocyte ratio, CRP, WBC, and ESR were 3.28, 2.32, 1.22, and 4.21 respectively. It has 85% sensitivity for detection of COPD exacerbation. and 89% specificity (AUC 0.798, p = 0.001). In conclusion, Blood NLR is a simple, inexpensive, widely available index that has been intensively evaluated in recent years in several clinical applications and in various diseases, including COPD.