The CYP2C9 and CYP2C19 polymorphism are associated with pretreatment drug response prediction, metabolism and disposition. Pakistan consists of a population comprising of various ethnic groups residing in different regions of the country each claiming diverse ethnic origins. The identification of the CYP450 genotypic composition of these populations is therefore necessary to avoid adverse drug reactions in these individuals. The study objective was to investigate the CYP2C9*2, CYP2C9*3, CYP2C19*2, CYP2C19*17 frequency in nine Pakistani ethnic groups and to check their association with hypertension. DNA was extracted and analyzed by AS-PCR. Four phenotypes were observed and they were: extensive metabolizer (EM), poor metabolizer (PM), intermediate metabolizer (IM) and ultra-rapid metabolizer (UM). Regarding population, over all the percentage of predicted PM allele (CYP2C19*2) was 29.0% compared to (CYP2C19*17) UM allele 23.70%. Among the studied groups, Saraiki and Brahui showed highest percentage of PM allele (40%, 36%) whereas Parsi and Hazara had highest percentage of UM allele (37% and 30% respectively). In case of CYP2C9, CYP2C9*2 showed highest frequency in Saraiki (51%) and Burusho (45%), while in case of CYP2C9*3 Brahui (49%) and Hazara (47%) showed highest frequency. Overall, 75%, 25%; 64.2%, 35.8 % of CYP2C19*2 and 66.6%, 33.4%; 75.6%, 24.4% of CYP2C19*17 wild type and mutant allele frequency was observed in patients and controls (p<0.05). Similarly, 51%, 49%; 76%, 24% of CYP2C9*2 and 46.5%, 53.5%; 46%, 54% of CYP2C9*3 wild type and mutant allele frequency was observed in patients and controls (p<0.05). In conclusion the high prevalance of CYP2C9*2, CYP2C9*3, CYP2C19*2 and *17 in Pakistani population leads to the recommendation of a pre-treatment test to monitor drug response and dosage (personalized medicine) to avoid post-treatment adverse drug reactions.