Thrombosis in children has multiple etiologies, including inherited disorders such as factor V Leiden mutation, prothrombin 20210A mutation, and deficiencies in protein C, S, or antithrombin. Epidemiology of the disorders varies, as does the risk of thrombosis. Venous thromboembolism is the typical presentation. However, more severe anticoagulant protein deficiencies may present with purpura fulminans. Treatment of thrombosis is relatively uniform, regardless of the underlying genetic risk factor. In this article, we discuss the most well-studied inherited thrombophilias and the epidemiology, pathophysiology, and relative thrombotic risk of each. Treatment of thrombosis is also briefly reviewed.