Warfarin is an anticoagulant.It was initially marketed as a pesticide against rats and mice and is popular for this purpose.

Warfarin is a synthetic derivative of , a 4-hydroxycoumarin-derived anticoagulant found in spoiled clover-based animal feeds. , in turn, is derived from , a chemical found naturally in many plants (not to be confused with Coumadin, a brand name for warfarin). Coumarin itself has no effect on clotting, or upon the action of warfarin. Warfarin and related 4-hydroxycoumarin-containing molecules decrease blood by inhibiting , an that recycles oxidized to its reduced form after it has participated in the of several blood coagulation proteins.                                                                                          

Rodenticide warfarin