Chronic anticoagulant treatment is administered mostly for cardiological reasons. Cumarin derivatires are used in the majority of cases (Warfarin, Pelentan). It is necessary to monitor this treatment regularly and to control the dose according to the INR value. Different complications can occur; the haemorrhage represents a serious one. The authors discuss several aspects of anticoagulant therapy and possible prevention of the complications. The importance of the problems is demonstrated on the authors’ clinical experience - two cases of haemorrhage after Warfarin administration simulating an acute surgical event.

        Key words: anticoagulant treatment - haemorrhage complications - „acute abdomen“