Thrombophilia can be defined as congenital and acquired disorders of the blood coagulation system which are associated with thrombosis. Numerous abnormalities linked with venous thromboembolism have been described recently. Among the different possibilities, it is crucial to order tests which can really modify the therapeutic attitude towards the patient and/or his family. The present review tries to provide some answers; however the recommendations should be considered as provisional, because new findings and study results will certainly modify them in the near future.