CYP2C19 is a hemoprotein participating in the first phase of biotransformation of xenobiotics and endogenous molecules and represents a large gene family CYP2C. The total share of the first phase of metabolic biotransformation with CYP2C9 make up 15%. CYP2C19 gene locus is located on chromosome 10q24 and consists of 9 exons. The gene encoding this enzyme is polymorphic and it is important for clinical practice because of the CYP2C19 enzyme involved in the metabolism of several important drugs. Genetic polymorphism of CYP2C19 is common in the general population with significant inter-ethnic variability in phenotype distribution. The incidence of slow metabolizers is 1-5%, 13-23%, 6% and 70% in Caucasian, Asian, Ethiopian, and Vanuatu population respectively. Previous researches suggest the presence of CYP2C19*2 and CYP2C19*3 in 95% of slow metabolizers. The most common polymorphic allele in the Caucasian population is allele 2C19*2 and 2C19*3 allele in Asian population encoding the inactive enzyme. Some of the most important protective factors in preserving the integrity of endothelium in blood vessels and hemostasis are products of arachidonic acid (AA), such as epoksieicosatrienoic acid that is metabolised by CYP enzymes. Mutant alleles CYP2C19*2 and CYP2C19*3 encode an enzyme with reduced activity that results in reduced concentration of EETs and increased concentration of proinflamatory cytokines (IL-6 and hs-CRP) consequently leading to rapid development and progression of atherosclerosis, which is a major etiologic factor of cardiovascular and neurovascular diseases (ACS, stroke). One of the substrates of CYP2C19 enzyme is antiplatelet drug clopidogrel, which prevents the development of thrombosis and is used in primary and secondary prevention of cardiovascular and cardioembolic events (eg. CE MU). Increased risk of these disorders is brought into connection with genetic resistance to clopidogrel as a result of the presence of at least one variant allele CYP2C19 *2 / *3.