Background: Cytochrome P450 2C9 (CYP2C9) is involved in metabolism of many important drugs and its genotype variations is thought to affect drug efficacy and the treatment process. Aim: The aim of this study was to assess the distribution of CYP2C9 allele and genotypic variants in Sistani ethnic group, living in Gorgan, South East of Caspian Sea and North East of Iran. Subjects and Methods: This study included 140 Sistani, referred to the health center of Gorgan. CYP2C9 genotyping was carried out by Polymerase Chain Reaction -Restriction Fragment Length Polymorphism technique. Results: The allele frequency of CYP2C9*1, CYP2C9*2 and CYP2C9*3 was 76.1%, 16.1% and 7.8%, respectively. The frequency of CYP2C9*1/*1,CYP2C9*1/*2, CYP2C9*1/*3, CYP2C9*2/*2, CYP2C9*2/*3 and CYP2C9*3/*3 genotypes was 53.9%, 22.1%, 11.4%, 2.9%, 4.3% and nil, respectively. Conclusions: Our findings demonstrate that different genotypes of CYP2C9 may influence the pharmacokinetics of some drugs. Determining the pharmacokinetic effects of CYP2C9 genotypes may help physicians choose optimal dosage of some drugs for treatment and prevention of their side effects. Since different ethnic groups from all over the world use medications, it is necessary to investigate the pharmacokinetic effects of CYP2C9 genotypes in different populations.