Chronic obstructive pulmonary disease (COPD) is an important public health problem and it is associated with systemic inflammation. Mean platelet volume (MPV) is one of the markers indicating platelet activation, and there are different results in different diseases related to inflammation. As for COPD some studies found it to be high whereas others found low results. In this study, we aimed to study parameters like MPV, platelet distribution volume (PDW), red blood cell (RBC), which are studied in the complete blood count testing routinely of patients with COPD, smoking and nonsmoking subjects without chronic diseases. Data of 121 patients with COPD, 101 nonsmoking subjects and 102 smoking subjects were retrospectively enrolled. Results were statistically analyzed. MPV levels were lower in patients with COPD compared with smokers (P<0.001) and nonsmoking subjects (P<0.001) but platelet levels were not significantly different. PDW levels found to be lower in COPD group compared with smokers (P<0.013) and nonsmokers (P<0.001). White blood cells were higher in patients with COPD as were expected (P<0.001). Neutrophil levels also were higher in patients with COPD compared with smokers (P<0.003) and nonsmokers (P<0.0001). RBC levels were lower in patients with COPD when compared with nonsmokers (P<0.001). The results of this study suggest that the decreased MPV and PDW may be used as negative reactants for evaluation of COPD.