Anticoagulant therapy is indicated in many clinical situations. The handling of vitamin K antagonists (VKA) is difficult and their therapeutic range is narrow, requiring close biological monitoring of INR. Introduction of VKA is a particularly critical period. Algorithms for initiation of oral anticoagulant therapy have been proposed but they are generally designed for warfarin, which has a longer half life as compared to acenocoumarol. In this article, algorithms for the prescription of acenocoumarol are proposed, taking into account the patient's age, weight and initial Quick value. The goal of these algorithms, combined with frequent monitoring of INR, is to limit the bleeding risk during the introduction of anticoagulant therapy.