Introduction. In 2021, the results of the first large-scale prospective cohort study were published showing the negative impact of post-diagnosis smoking on the prognosis of non-small cell lung cancer (I-IIIа). The purpose of the study is to assess the possible benefits of postdiagnosis smoking cessation of patients with non-small cell lung cancer (NSLC) stage I–IIIa to both the health care system society as a whole. Materials and methods. A mathematical model (calculator) has been developed to calculate the economic benefits of smoking cessation among patients with a confirmed diagnosis of NSCLC (I–IIIa). The calculator uses indicators characterizing the postdiagnosis smoking status of patients with stage I–IIIa NSCLC, the probability of disease progression and survival in the groups of those who continue to smoke and those who quit smoking. These data were obtained from the prospective epidemiologic study performed in the department of clinical epidemiology, N. N. Blokhin NMRC of oncology in cooperation with the IARC. The calculator takes into account the average cost of treating patients with late-stage NSCLC (IIIb-IV stage) in 2020–2022, which is calculated based on an analysis of the medical records of patients who were treated in the Department of Medical Cancer Therapy No. 3 of the of the Federal State Budgetary Institution «N. N. Blokhin National Medical Research Center of Oncology» (Head K. K. Laktionov), statistical data on incidence and mortality from NSCLC in Russia, the Gross Domestic Product (GDP) per capita indicator, and the MINEC Forecast of socio-economic development of the Russian Federation for 2023, 2024 and 2025. Results. Stopping smoking after diagnosis of NSCLC stage I–IIIa results in cost savings due to a reduced likelihood of relapses and an increased number of patients who avoid relapses when quitting smoking. Taking into account the fact that the average cost of treatment for patients with stage IIIb–IV NSCLC is 4,000,000 rubles, savings on treatment due to a decrease in the likelihood of relapses and as a result of an increase in the number of relapse-free patients who quit smoking amounted to 3,321 million rubles. and 9,251 million rubles, respectively, per year. Thus, the total cost savings on treatment will amount to 12,588 million rubles or slightly more than 2.3 million rubles per patient who quit smoking. The second source of saving is maintaining the economically active potential of some patients diagnosed with stage I–IIIa NSCLC, due to increased progression free survival as a result of smoking cessation аmounts to 3 304 million rubles per year in terms of per capita GDP. If 100 % of patients with stage I–IIIa NLCLC hypothetically quit smoking, the potential budget savings could reach a significantly greater value of 29,480 million rubles per year. The economic benefit to society in the total metric of per capita GDP, obtained as a result of increased survival and possible preservation of labor activity, could exceed 14 billion rubles over a 5-year period. Conclusion. Smoking cessation in cancer patients is accompanied not only by clinical benefits, i. e. it reduces mortality and improves survival rates, but also by economic benefits for the healthcare system and the country as a whole.