It is known that SARS-CoV-2 affects the respiratory tract and causes pneumonia and respiratory failure in patients.Smoking increases susceptibility to many respiratory diseases, including infections, and affects the prognosis and mortality of these diseases.The increased levels of angiotensin converting enzyme-2, which is a binding receptor for SARS-CoV-2 in the lungs, suggest that smoking has negative effects on patients with COVID-19.In this review, the relationship between smoking and COVID-19 is examined with a review of current literature.