To determine the diagnostic and prognostic value of fibrinopeptides in patients with clinically suspected pulmonary embolism (PE), we made a pilot study in the Emergency Department with a general ICU. 32 patients with clinically suspected pulmonary embolism were the participants and 16 cases were diagnosed as PE-positive. After the diagnosis of PE, thrombolytic therapy with urokinase was administered, followed by heparin therapy. Plasma fibrinopeptide A (FPA) and fibrinopeptide B beta 15-42 (FPB beta 15-42) were measured before treatment and at 1, 2 and 6 days after treatment. In the PE-positive patients, the levels of both fibrinopeptides measured prior to the treatment were above the normal values, and were significantly higher than those of PE-negative patients. When the cutoff points of FPA and, FPB beta 15-42 were set at 15 ng/ml, 15 ng/ml respectively, both markers had a high sensitivity, a highly negative predictive value and a moderate specificity. Six of the PE-positive patients died. The FPB beta 15-42 levels were significantly lower in the survivors than those in the patients who died at 2 days (p = 0.0092) and 6 days (p = 0.0011). We can conclude that: 1) the fibrinopeptide measured in this study are useful for screening for PE; and 2) FPB beta 15-42 may possibly be useful as a method for predicting the clinical outcome of PE.