Objective To investigate the distribution status of cytochrome CYP2C19 polymorphisms among patients with cardio-vascular diseases in Dongguan area .Methods A total of 1662 patients with cardiovascular diseases (CVD) in our hospital were se-lected .The peripheral blood was collected for extracting genomic DNA .The CYP2C19 genotype was detected by the polymerase chain reaction (PCR) combined with gene chip technology .The allele frequency and metabolic phenotype of CYP2C19 were com-pared between the CVD patients aged lower than 45 years and aged higher than 45 years old .Results Among 1662 cases ,713 cases (42 .90% ) were CYP2C19 extensive metabolizer ,740 cases(44 .52% ) were moderate metabolizer and 209 cases (12 .58% ) were poor metabolizer .The allele frequencies of CYP2C19﹡1 ,CYP2C19﹡2 and CYP2C19﹡3 were 65 .16% ,30 .08% and 4 .75% re-spectively .One hundred and four cases (40 .00% ) of extensive metabolisms were detected in the lower than 45 years old group ,104 cases(45 .38% ) of moderate metabolisms and 38 cases (14 .62% ) were detected .In the higher than 45 years old group ,609 cases (43 .44% ) of extensive metabolisms ,622 cases of moderate metabolisms and 171 cases(12 .20% ) of poor metabolism were detec-ted .The proportion of various genotypes had no statistical difference between the lower than 45 year old group and higher than 45 year old group(P>0 .05) .Conclusion Detecting CYP2C19 genotype for determining the genetic characteristics can evaluate the clopidogrel resistance risk and formulate the personalized anti-platelet therapeutic scheme .