Background and objective - Warfarin is a commonly used oral anticoagulant with a narrow therapeutic index and various genetic and clinical factors that influence interpatient variability in dose requirements. This study investigated the impact of genetic and nongenetic factors on warfarin dose requirements in Egyptians.Methods—DNA was extracted from 50 patients taking warfarin for more than 1 year and genotyped for VKORC1 (1173 C>T), CYP2C9 *3 (1075 C>A) gene polymorphisms using SYBR Green-based multiplex allele-specific PCR. Linear regression modeling was conducted to identify the genetic and nongenetic factors that independently influence warfarin dose requirements.Results— (76%) of the patients had VKORC1 TT variant , carriers of the VKORC1 TT genotype had a significantly lower weekly maintenance dose of warfarin than those carrying the CT/CC genotypes (P = 0.032). The CC variant was noted in 22% of participants and the CT variant was noted only in 2% of participants in the present study. (86%) of the patients had wild-type CYP2C9*1/*1, (14%) were heterozygotes CYP2C9 *1/*3 and the variant CYP2C9 *3/*3 was not found in any of the patients in this study. It was found that this gene was not considered a covariate for warfarin maintenance dose in the Egyptian population (P=0.925). Age was the only of the non genetic factors that has been found to influence warfarin dosing, the dose requirements decrease with age (P = 0.013).Conclusion—The study shows that VKORC1 polymorphisms and age are important determinants of warfarin dose requirements in Egyptian patients.