Maintenance of normal blood flow requires equilibrium between procoagulant and anticoagulant factors; occasionally, procoagulant activity predominates, leading to clot formation; frequently, tissue damage is the triggering factor. Hereditary factors, primary or acquired, play a role in the development of thrombosis. Primary thrombophilia is associated with hereditary factors, which promote hypercoagulability because natural anticoagulants are not exerting their activity. On the other hand, acquired thrombophilia may occur associated to autoimmune diseases, cancer, surgical procedures, pregnancy, postpartum period, and obesity. Activation of the coagulation system is characterized by the co-participation of inflammatory response components, factors related to the subjacent disease, and other procoagulant factors. The study of patients with thrombosis should include both inflammatory and autoimmune response markers.