SUMMARY OBJECTIVE: We aimed to explore the prevalence of smoking rates and comorbidities and evaluate the relationship between them and disease severity and mortality in inpatients with COVID-19. METHODS: COVID-19 patients were divided into the following groups: clinic group, intensive care unit (ICU) group, survivors, and non-survivors. Non-COVID-19 patients were included as a control group. The groups were compared. RESULTS: There was no difference between patients with and without COVID-19 in terms of smoking, asthma, diabetes, dementia, coronary artery disease (CAD), hypertension, chronic renal failure and arrhythmia (p>0.05). Older age (Odds ratio (OR), 1.061; 95% confidence interval (CI): 1.041-1.082; p< 0.0001), chronic obstructive pulmonary disease (COPD) (OR, 2.775; 95% CI: 1.128-6.829; p=0.026) and CAD (OR, 2.696; 95% CI: 1.216-5.974; p=0.015) were significantly associated with ICU admission. Current smoking (OR, 5.101; 95% CI: 2.382-10.927; p<0.0001) and former smoking (OR, 3.789; 95% CI: 1.845-7.780; p<0.0001) were risk factors for ICU admission. Older age (OR; 1.082; 95% CI: 1.056-1.109; p<0.0001), COPD (OR, 3.213; 95% CI: 1.224-8.431; p=0.018), CAD (OR, 6.252; 95% CI: 2.171-18.004; p=0.001) and congestive heart failure (CHF) (OR, 5.917; 95% CI 1.069-32.258; p=0.042), were significantly associated with mortality. Current smoking (OR, 13.014; 95% CI: 5.058-33.480; p<0.0001) and former smoking (OR, 6.507; 95% CI 2.731-15.501; p<0.0001) were also risk factors for mortality. CONCLUSION: Smoking, older age, COPD, and CAD were risk factors for ICU admission and mortality in patients with COVID-19. CHF was not a risk factor for ICU admission; however, it was a risk factor for mortality.