Background: While it is well known that systemic steroids may cause changes in hemogram parameters, it is essential whether the use of inhaled corticosteroid (ICS) leads to changes in hemogram parameters.In this study, we aimed to find out the effects of ICSs on hemogram in the comparison between different inhaler techniques of different corticosteroids.Methods: The medical records of 100 ICS user COPD patients and 100 ICS non-user COPD patients were reviewed retrospectively.Demographic data, complete blood count values, GOLD groups, history of pneumonia in the last year, the content of bronchodilator treatments and valid inhaler techniques were recorded.Results: Significant increase was detected in the mean MCHC, Eosinophil%, Eosinophil values among ICS non-users; and the mean RDW-CV, MCV, WBC, Neutrophil% and Neutrophil values among ICS users (p<0.05).Anaemia was observed in 16(%) of ICS non-users and 31(%) of ICS users (p=0.05).Fluticasone propionate group had the highest rate of pneumonia in the last year (11.1%) (p=0.05).WBC, Neutrophil%, Neutrophil were significantly lower in budesonide group (p=0.012,p=0.05, p=0.048 respectively).The mean Monocyte% and Monocyte were significantly lower in beclomethasone group (p=0.043,p=0.05, respectively).Nebulizer users had the highest frequency of pneumonia diagnosis in the last year (30%) (p=0.05).The mean WBC was significantly higher in blister-based DPI users (9.4±2.3x10 3 cell/µL) (p=0.044).The frequency of pneumonia was increased by 3 fold/year in ICS users.Among the ICS users, the mean WBC and Neutrophil values of these 9 patients were significantly higher than those without pneumonia history (10.8±2.5 x10 3 cell/µL and 6.3±2.3 x10 3 cell; p=0.042 and p=0.05, respectively). Conclusion:The results of the study indicate that changes in hemogram parameters may be associated with ICS use and that these changes may be helpful in predicting systemic side effects of ICSs.