Tobacco smoking is a major preventable risk factor for non-communicable diseases. The aim of this study was to investigate predictors of tobacco smoking among acute medically ill patients admitted to a Moscow hospital, and the association between smoking and alcohol use.Patients admitted to the V. P. Demikhov hospital in Moscow from November 2016 through December 2017 were asked to participate in this study (inclusion criteria were acute medically ill patients aged ≥18 years). Sociodemographic data were collected, in addition to questionnaires on mental distress (Hopkins Symptom Checklist 5), alcohol use (Alcohol Use Disorder Identification Test 4, AUDIT-4) and smoking (Fagerström Test for Nicotine Dependence).A total of 3009 patients were recruited to the study. Using a binary logistic regression model adjusted for all variables, it was found that living without a partner resulted in a higher risk of smoking tobacco compared to being married or living with a partner (odds ratio, OR=1.60 for divorced, p=0.001; and OR=1.62 for single, p=0.002), and being economically non-active resulted in a higher risk compared to being economically active (OR=1.47; p=0.003). Harmful alcohol use (AUDIT-4 score ≥5 [for females] / 7 [for males]) resulted in a higher risk of smoking compared to those without harmful alcohol use (OR=4.04; p<0.001).Smoking was highly prevalent and associated with other adverse sociodemographic and lifestyle factors such as harmful alcohol use.