INTRODUCTION Chronic obstructive pulmonary disease (COPD) is the most important lung disease leading to disability and even death. Recent studies have shown that the platelet indices are associated with several cardiovascular diseases; however, there is little data on COPD. OBJECTIVES We aimed to explore the relationship between platelet indices, together with the platelet-to-lymphocyte ratio (PLR), white blood cell count to mean platelet volume ratio (WMR), and red cell distribution width (RDW) and the severity of COPD. PATIENTS AND METHODS This retrospective study was based on data collected from a total of 153 COPD patients admitted to our outpatient clinic between March 2014 and March 2015. All of the participants underwent pulmonary function tests; FEV1, FVC, and FEV1/FVC were measured. The study population was divided into four according to the severity of COPD as group A (mild), group B (mild to moderate), group C (moderate to severe), and group D (severe). RESULTS A significant increase was found in platelet distribution width (PDW), MPV, plateletcrit, PLR, and RDW while WMR decreased as the COPD severity increases. In the multiple logistic regression analysis, we found that PDW and RDW were independently associated with the presence of severe COPD. ROC curve analysis showed that a PDW>14.85 was associated with severe COPD with 85% sensitivity and 86% specificity while RDW>14.45 was associated with severe COPD with 90% sensitivity and 87% specificity. CONCLUSIONS The PDW and the RDW are independently associated with disease severity, which may indicate hypoxemia, underlying inflammation, and oxidative stress in COPD.