Plasma levels of prothrombin fragment 1+2 (Fl+2), thrombin-antithrombin complexes (TAT) and D-dimers were measured in 15 patients with pulmonary embolism during heparin therapy, oral anticoagulation, and after cessation of warfarin therapy. Each patient had a favorable outcome during anticoagulant therapy (3 months), but late venous thromboembolism occurred in six cases. The mean levels of the three markers were significantly increased on day 4 after the thrombotic event, and normalized during warfarin therapy. Nine months after the initial pulmonary embolism, mean levels of the three markers, as compared with a control population, were significantly higher in the patients with late recurrences, whereas only TAT were slightly higher in patients without recurrences as compared with controls. Only TAT levels were significantly higher in the patients with late recurrences than in those without late recurrences. Thus, the levels of the three markers 9 months after pulmonary embolism seem to be interesting to identify patients with high risk of recurrence and who might require longer anticoagulant treatment.