A 4-hydroxycoumarin derivative with anticoagulant activity. As a vitamin K antagonist, acenocoumarol inhibits vitamin K epoxide reductase, thereby inhibiting the reduction of vitamin K and the availability of vitamin KH2. This prevents gamma carboxylation of glutamic acid residues near the N-terminals of the vitamin K-dependent clotting factors, including factor II, VII, IX, and X and anticoagulant proteins C and S. This prevents their activity and thus thrombin formation. Compared to other coumarin derivatives, acenocoumarol has a short half-life.