The limitations of traditional anticoagulants, heparin and warfarin, have prompted the development of new anticoagulant drugs for prevention and treatment of both venous and arterial thromboembolism. After a brief review of thrombogenesis and its regulation, this paper focuses on new anticoagulant agents in more advanced stages of clinical testing.British Journal of Pharmacology (2005) 144, 1017-1028. doi:10.1038/sj.bjp.0706153 [ABSTRACT FROM AUTHOR]