The aim of this study was to determine the extent of tobacco and drug addiction to opium, methamphetamine and heroin in hospitalized patients due to COVID-19. In this cross-sectional descriptive study, the rate of smoking and drug addiction among COVID-19 patients admitted to Shahid Sadoughi hospital in Yazd was investigated. A total of 500 patients were studied and patient information such as smoking and drug use history, dosage, type of substance, length of hospital stay and severity of the disease were extracted in this paper. Then the data were entered into SPSS software and analyzed. No significant relationship was found between patients sex (Main genetic factor) and smoking with disease severity. Also, no significant relationship was found between smoking and length of hospital stay. Also, there was no significant difference between the severity of clinical symptoms in drug users and other subjects. In this study, the prevalence of smoking among COVID-19 patients was about 6.6 %.