Background: Clopidogrel is a standout amongst the most ordinarily recommended medications to avoid ischemic occasions taking after coronary disorder or stant position. However, impaired responses the therapy as well as resistance to the therapy have also been reported. Genetic variants play an important role in clopidogrel biotransformation of its active metabolite that may subsequently influence the antiplatelet effect of clopidogrel. The objective of this study was to evaluate the prevalence of the cytochrome P450 (CYP450) 2C19 enzyme (CYP2C19) genotypes which are involved in the activation of clopidogrel in a random Iranian population of various ethnic groups (Persian, Azari, Kurd, etc.). Molecular analysis of CYP2C19 polymorphisms may be helpful in the determination of optimal antiplatelet therapy.

Materials and Methods: CYP2C19 (*1/*2/*3) variants were assessed by Polymerase Chain Reaction-Restriction Length Polymorphism (PCR–RFLP) assays in a representative sample of 154 Iranian patients with ischemic heart disease.

Results: The frequencies of CYP2C19 *1 (normal genotype), *2 (heterozygote) and *3 (homozygote) were 112 (72.7%), 36 (23.4%) and 6 (3.9%), respectively.

Conclusion: The United States Food and Drug Administration (FDA) recommendations are more useful to be practiced in our country compared with other countries. Physicians should identify poor metabolizers for consideration of other antiplatelet medications or alternative dosing strategies.