Objective: In smokers, COVID-19 may have a more severe course due to impaired mucociliary activity, increased permeability, and inflammation of the airway epithelium. However, data on the impact of smoking in patients with COVID-19 pneumonia are conflicting. The study aimed to evaluate the effects of smoking on laboratory parameters, intensive care unit (ICU) length of stay, length of hospital stay, and mortality in COVID-19 patients hospitalized in the intensive careunit. Methods: Medical records of 576 patients who were followed up in the ICU for COVID-19 between January and September 2021 were analyzed retrospectively. Demographic data, comorbidities, laboratory parameters (hemoglobin, white blood cell (WBC), lymphocyte, neutrophil, thrombocyte, AST, ALT, CRP, D-dimer, ferritin, BNP, albumin), ICU and hospital stay of the patients were recorded. The patients were divided into 2 groups according to whether they smoked or not. Results: The data of 576 patients were evaluated in the study. The mean age of the patients was 69±14.8 years, and 53.8% were male. The smoking rate was 30%, and the smoking rate in men was 76.9%. The intensive care unit admission age of smokers was lower than non-smokers (p=0.01). The presence of coronary artery disease (CAD), chronic obstructive pulmonary disease (COPD), and malignancy was significantly higher in smokers. Among the laboratory parameters, white blood cell count (WBC) and neutrophil were higher in smokers (p=0.01). There was no relationship between ICU length of stay, length of hospital stay, and mortality in smokers (p=0.769, p=0.699, p=0.852, respectively). Conclusion: We did not find any significant association between smoking and COVID-19 mortality. We recommend clinicians to monitor WBC and neutrophil count closely as markers of possible progression to critical illness in patients hospitalized in the ICU due to smoking COVID-19.