Acute coronary syndrome (ACS) represents one of the principal causes of demanding emergency services, being as well the most frequent cause of the sudden death of the adult. ACS is defi ned through association of at least two from the following three criteria: presence of a thoracic pain at rest that lasts at least 24 hours, being of coronary origin, characteristic electrocardiographic modifi cations, emphasizing of myocardial ischaemia through biological markers. The new classifi cation of ACS includes: ACS with a sublevel-change of ST segment that corresponds to myocardial infarction and ACS without any sub-levelchange of ST which corresponds to unstable angina pectoris. Epidemiological evolution of ACS in Europe is characterized by decrease of acute myocardial infarction incidence and increase of unstable angina pectoris and myocardial infarction incidence. The early reperfusion of the myocardium has considerably improved the prognosis of acute myocardial infarction. Creation of emergency medical assistance systems that would provide an early diagnosis, correct clinical assessment and stratifi cation of coronary event risk, applying of an adequate prehospital treatment and hospitalization of the patient in intensive cardiological therapy conditions represent the major objectives in limiting necrosis zones and prophylaxis of major coronary accidents such as sudden death and acute myocardial infarction. ACS with sub-level- change of ST segment or ACSST corresponds to a complete coronary occlusion with a thrombus and it requires an emergency reperfusion. ACS without sub-level-change of ST segment or ACSSTcorresponds to a partial or transient coronary occlusion. Two types of therapeutical coronary reperfusion are available: a) pharmacological reperfusion (thrombo lysis). b) invasive reperfusion – primary angioplasty with coronary stent. Development of emergency prehospital and cardiological services with the possibility of an interventional cardiology will provide the achievement of mortality reduction due to ACS.