Objective — to provide an objective assessment of the results of high-quality assistance in quitting smoking and to study the determinants of the effectiveness of appropriate assistance. Material and methods. The results of providing high-quality assistance in smoking cessation were analyzed in 524 adult smokers followed up within for 6 months or more after they had been given appropriate help. Most people (65%) receiving professional assistance in quitting smoking achieved these and those results: 19% of the study participants could show a 2-fold reduction in the number of cigarettes smoked; more than 46% completely gave up smoking during different periods; 38 and 24% stopped smoking more than 1 month and more than 6 months, respectively. Results. The effectiveness of stop-smoking assistance was found to be influenced by factors, such as age, gender, some characteristics of a smoking history, degree of tobacco dependence, and level of motivation to give up smoking. Odds ratio (OR) calculation showed that the likelihood of successful quitting reduced with a smoking intensity of more than 10 cigarettes per day (OR, 0.57; 95% CI, 0.31—1.02) and with high tobacco dependence (7 scores) estimated by the Fagerström test (OR, 0.64; 95% CI, 0.37 to 1.07). At the same time, the likelihood of successful smoking cessation substantially increased with a history of previous successful quit attempts for a particular period of time (OR, 3.71; 95% CI, 1.70—8.12) and with rather high motivation towards smoking cessation (OR, 4.3; 95% CI, 1.92—5.61). Conclusion. The fundamental determinant of the effectiveness of smoking quit attempts is the degree of motivation and psychological readiness for smoking cessation. The investigation proposes guidelines to enhance the effectiveness of high-quality assistance in giving up smoking.