Several international studies have already confirmed the importance of the socioeconomic status of acute myocardial infarction patients in terms of patient care and prognosis. To our knowledge, a nationwide examination of this kind has not yet taken place in Hungary. The investigation of this problem field was made possible by the fact that from January 1, 2014, all healthcare providers must record the data of patients treated with a diagnosis of acute myocardial infarction in the database of the Hungarian Myocardial Infarction Registry (HUMIR). In this study, the authors searched for an answer to whether the complex development index (CDI) in Hungary's 174 districts and 23 capital districts influences the treatment and prognosis of acute myocardial infarction patients. Based on the CDI worked out by the Hungarian Central Statistical Office, the authors divided the Hungarian districts into low (CDI_L), medium (CDI_M) and high (CDI_H) CDI groups according to their values. They examined the incidence, hospital treatment and prognosis of acute myocardial infarction in these administrative-territorial units. The HUMIR included 66,253 patients treated by myocardial infarction between 2015 and 2019. Their place of residence could be identified based on the zip code and in which district it was located. In the examined population, 29,101 patients with ST-elevation (STEMI) and 37,152 without ST-elevation (NSTEMI) received treatment for acute myocardial infarction. In the population over 15 years of age, the age-standardized incidence of STEMI was 68.8 per 100,000 inhabitants a year in the CDI_L group and 52.7 per 100,000 inhabitants a year in the CDI_H group. Almost the same values were found in all three CDI subgroups of NSTEMI incidence (69.5 and 67 per 10,000 inhabitants a year). The frequency of percutaneous coronary intervention in the case of STEMI was higher than in NSTEMI, but within the groups, CDI did not influence the performance of this treatment. In the case of STEMI, the rates of patients who underwent percutaneous coronaria intervention in all three CDI subgroups (CDI_L, CDI_M, CDI_H) were 83.5%, 83.7%, 83.5%, while in the case of NSTEMI they were 57.4%, 57.7%, 57.3%. The authors applied a Cox multivariate regression analysis to examine myocardial infarction mortality. The CDI did not affect the 30-day mortality rates in the case of any myocardial infarction: the hazard ratio (HR) values were 0.906 and 0.914 (p = 0.04659; p = 0.04686) in the case of STEMI, while 1.067 and 1.001 (p = 0.16520; p = 0.98933) in the case of NSTEMI. In the case of a STEMI diagnosis, the risk of the 30-364-day and the 1-year mortality in the subgroup of CDI_H was significantly lower (HR = 0.822 and 0.816) than in the subgroup of CDI_L (p = 0.00096 and p = 0.00001). In the case of NSTEMI diagnosis, the authors found a difference in the risk of beyond 1-year mortality by comparing the districts in the subgroup of CDI_L with the districts in CDI_H: in the latter case, the HR of the mortality was 0.876, which was significantly lower (p = 0.00029) than in the subgroup of CDI_L. The CDI has independent prognostic significance in determining the late prognosis of acute myocardial infarction patients. Orv Hetil. 2022; 163(47): 1862-1871.