Thrombophilia is a multifactorial predisposition for thromboembolism affecting about a tenth of any population. We investigated whether genetic counseling combined with molecular testing for two common dominant mutations (coagulation factor V Leiden and prothrombin G20210A) may increase prevention of venous thromboembolic incidents in individuals with a positive family history compared to the general population.Mutation detection was carried out by Restriction Fragment Length Polymorphism analysis in DNA samples of 96 unrelated healthy Greeks (group A) who asked for genetic counseling for various reasons and had at least two relatives with thromboembolic incidents and 100 unrelated healthy Greeks (group B).In group A, both mutations were detected at five-fold higher frequencies (33.33% for Leiden and 19.79% for G20210A) compared to group B, which had frequencies typically found in the Greek population (6% and 4%, respectively).In populations with a high prevalence for these two common mutations, genetic counseling and molecular testing of at-risk individuals may significantly increase prevention of thromboembolic disease.