Aim: Cigarette smoking is associated with an increased risk of cardiovascular diseases, including coronary artery disease, peripheral vascular disease, ischemic heart disease, atherosclerosis, myocardial infarction, and stroke. Our aim was to define possible effects of smoking on hematological parameters as well as ferritin and transferrin saturation. Methods: This study was performed in a retrospective manner. One hundred and forty-nine patients, who were admitted to Hacettepe University Hospitals between September 2018 and November 2018, were evaluated. Results: There were 95 (63.7%) healthy non-smokers and 54 (36.3%) healthy smokers included in this study. The median age was 32 (18-61) years for all groups. There were 47 (31.5%) males and 102 (68.5%) females in this study. Hemoglobin (p<0.001), hematocrit (HCT) (p<0.001) and mean corpuscular volume (MCV) (p=0.002) values were statistically significantly higher in smokers-group than in non-smokers group. Leukocyte (p<0.001), neutrophil (p=0.001) and lymphocyte (p=0.04) counts were statistically significantly higher in smokers group compared to non-smokers group. Conclusion: Our study showed that cigarette smoking has severe adverse effects on hematological parameters such as hemoglobin, leucocytes, lymphocytes, MCV and HCT. These alterations might be associated with a greater risk of developing secondary polycythemia, atherosclerosis, chronic obstructive pulmonary disease and cardiovascular diseases.