In the past decade development of aptamer technology is poised into several fields with various clinical applications. With this progress, aptamer based anti-coagulant agents are evolved and continuing their applications with clinical trials. At present several anti-coagulant aptamers are available against different proteins from blood coagulation cascade. In this review, the mechanism and functions of anti-coagulant aptamers, as an alternate candidate to other available anti-coagulant agents are discussed.