A descriptive observational study was conducted with a targeted examination of a random sample of adults who underwent medical dispensarization in 2017—2018 in two municipal clinics in Moscow. The number of the studied sample was 1020 people (402 men and 618 women) aged 18—81 years. By the method of formalized interviewing using a unified questionnaire, data were collected on the smoking habits and medical history of individuals included in the study. In the studied sample, the percentage of smokers was 37.9, past smokers and those who quit smoking more than a year ago — 25.5 and never smoked — 36.6. The number of smokers was 54.2% among men (95% CI 49—59%) and 27.3% among women (95% CI 24—31%). Among all non-smokers, 50% (95% CI 46—54%) were passive smokers. By calculating the odds ratio (OR) indicators, an assessment was made of the relationship between the nature of smoking history and the probability of developing certain groups of diseases. So, in smokers, compared with non-smokers, the probability of tobacco-dependent forms of malignant tumors, OR 1.60 (95% CI 1.00—2.55), heart and vascular diseases, OR 1.36 (95% CI 1), 22—3.62), bronchopulmonary diseases, OR 6.70 (95% CI 4.37—10.26) significantly increased. It was also established that the probability of developing certain types of diseases increased with an increase in the duration of smoking.