Chronic Obstructive Pulmonary Disease (COPD) is one of the top three causes of death worldwide that induces an economic and social burden which is both substantial and increasing. Hematological status may be altered even in stable COPD and which is inversely related with the forced expiratory volume in first one second of expiration (FEV1). The objective of the study was to assessthe hematological status in stable COPD patients by counting their neutrophil, lymphocyte and platelet and to correlate them with FEV1. This cross-sectional study was conducted in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Bangladesh from January 2010 to December 2010. Sixty (60) male smoker (5-10 pack /year) patients of stable COPD (FEV1/FVC% <0.70; FEV1 ≤80%; without any exacerbation for last 4 weeks) were randomly selected from the Out Patient Door (OPD) of Medicine Department, BSMMU and a private clinic in Dhaka. On the basis of spirometric findings, 30 mild (Group B1) and 30 moderate stages (Group B2) of COPD patients with age 35-45 years were included in this study. As control (Group A) 30 apparently healthy male persons with matched age, BMI and smoking status were studied. Neutrophil and lymphocyte were counted manually by compound microscope, slide and Leishman’s stain. Total count of platelet was counted manually by using hemocytometer and platelet counting fluid through direct method. Data was expressed as mean±SD. The mean±SD of neutrophil were 52.3±4.82, 57.3±5.09 and 71.0±5.5; lymphocyte were 30.7±5.37, 28.4±6.98 and 22.5±4.40% and platelet count were 207.3±19.66, 242.5±40.32 and 281.8±55.46 per mm3 of blood in Group A, B1 and B2 respectively. For statistical analysis Independent sample t-test and Pearson’s Correlation Coefficient test were performed, as applicable and p<0.05 was accepted as significant. In this study, the mean values of differential count of neutrophil were higher and lymphocytes were lower in both the study groups than control and also in B2 to that of the B1. The mean values of platelet were higher in both control and also in B2 to that of the B1. These differences of mean values among the groups were statistically significant at (p<0.001) in A vs. B1 and A vs. B2 but at (p<0.01) in B1 vs. B2. However, this result was non significant for lymphocyte count in B1. Hematological status altered in stable COPD and this alteration is inversely related to the severity of the disease.