One of the deleterious effects of the combined oral contraceptives is venous thromboembolism (VTE) and it is the most frequent. VTE is potentially serious because it is sometimes responsible for fatal pulmonary embolism. Because of the large use of hormonal contraception among healthy women and often for long durations, it is fundamental to target the prescriptions and detect women at high risk of VTE. It has been demonstrated that some congenital or acquired coagulation anomalies are associated with an increase of thromboembolic risk. In addition, combined oral contraceptives modify some parameters of the hemostasis, whatever the route of administration. In order to optimize the benefit-risk balance of oral contraception, the search for a biological thrombophilia is essential in some clinical situations such as in young women with a history of venous thromboembolic event or with a family history of thrombosis at a relatively young age. A thorough questioning must be performed. On the other hand, this biological research is not systematically recommended before any prescription of hormonal contraception in patients having neither previous personal nor family history of venous thrombosis.