The aim of this investigation performed in 75 outpatients taking oral anticoagulant after an episode of pulmonary embolism was to specify the modalities of ambulatory monitoring during oral anticoagulation. All patients were followed up by their family doctor after hospital discharge. The principal results of this investigation were (1) the general difficulty of obtaining and maintaining anticoagulation stability in a recommended therapeutic range (INR 2-3) for venous thromboembolic disease, (2) that in only 15% of personal anticoagulation notebooks were the laboratory results expressed in INR, (3) the lack of information given to the patients taking oral anticoagulant. Based on these results we started an education programme for nurses and physicians designed to promote the use of INR and to improve the quality of information given to anticoagulated patients. A new anticoagulation monitoring notebook should help medical staff and patients to increase the safety of anticoagulation.