Introduction: Despite positive trends in treatment, cardiovascular diseases are the top cause of death globally, taking about 17.9 million lives each year. In the European Union cardiovascular diseases are a sole culprit of basically 40% of all deaths. Objective: To determine the frequency of patients with myocardial infarction treated at the County Hospital Čakovec. In addition, one of research aims is to make a comparison of patients with ST-elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI) – taking into account their age, sex, the affected region of the heart muscle and the affected region of each coronary artery separately. Case report was also included in this thesis. Materials and methods: The research was conducted by analyzing the medical documentation from the hospital information system of the Čakovec County Hospital, the use of which was previously approved by the hospital committee. Data processing was performed using Microsoft Office Excel 2013 program. Results: In this period, 275 percutaneous coronary interventions (PCI) were performed for acute coronary syndrome (ACS). STEMI was diagnosed in 64 cases, while NSTEMI was diagnosed in 211 cases. The mortality rate from ACS in the coronary unit was 4%, while in the same period of time mortality rate in coronary angiography with PCI performance was 2%. It was found that the incidence of the STEMI diagnosis was 49 per 100,000 inhabitants while the incidence of NSTEMI diagnosis was 155 per 100,000 inhabitants. Conclusion: By analyzing the data obtained by the retrospective study, it can be concluded that the incidence of STEMI diagnosis is nearly two-thirds lower than NSTEMI diagnosis. One interesting fact is that the average age of men with a STEMI diagnosis is 63, which means that a large part of the patients are still working.