Venous Thrombosis is a major cause of mortality and morbidity in Western populations and in 30% of cases is associated to genetic susceptibility. Ideally, the identification of carriers of such susceptibility, known as thrombophilia, may allow for predicting the likelihood of recurrence in symptomatic patients and the risk of thrombosis in their relatives, leading to tailored plans of therapy and prophylaxis. In practice, this is greatly complicated by the high heterogeneity of both genotype and phenotype of inherited thrombophilia and by the lack of evidence-based guidelines for managing carriers. These issues and their impact on the process of genetic counseling for individuals suspected to have an inherited thrombophilia are discussed.