Background: Thrombophilias are hereditary or acquired conditions which can increase the risk of venous or arterial thrombosis. As the etiology of thrombosis is multifactorial, the presence of a thrombophilic defect is only one of many elements that determine risk. Therefore, the utility of testing for thrombophilia to inform prevention and treatment decisions is controversial. The aim of this work was to study epidemiological aspects and genetic mutation of inherited thrombophilia in Egyptian patients. Methods: The present study represents a case control study and was approved by the ethics committee on research involving human subjects of Benha Faculty of Medicine. Written informed consents were obtained from all participants. it was conducted on 64 cases with unexplained deep venous thrombosis any site all over the body with age ranged from 16 to 40 years. 59.4% of them were males and 40.6% were females. Results: Of all these defects in 56 cases of our study; MTHFR C677T mutation was the most frequent defect, then MTHFR A1298C, FVL, FXIII V34L, beta fibrinogen and prothrombin G21211. Conclusion: We found that MTHFR C677T mutation is important risk factor for thrombosis in Egyptian patients. The presence of this polymorphism can increase the risk of thrombosis. Patients with thrombosis at any site of their body have a significantly higher prevalence of MTHFR C677T mutation, FVL, FXIII V34L, beta fibrinogen and prothrombin G21211 compared to healthy controls. Of all these defects; MTHFR C677T mutation was the most frequent defect.