Objectives: The D-dimer level, fibrinogen level, and D-dimer/fibrinogen ratio are used in the diagnosis of pulmonary embolism, but results vary. We evaluated these parameters in the diagnosis of pulmonary embolism in emergency clinic patients. Methods: In this prospective study, 200 patients (pulmonary embolism, 100 patients; no pulmonary embolism, 100 patients) had D-dimer and fibrinogen levels measured before intervention. Pulmonary embolism was diagnosed with computed tomography angiography or ventilation-perfusion scintigraphy. Results: Compared with patients who did not have pulmonary embolism, patients who had pulmonary embolism had significantly greater mean D-dimer level (pulmonary embolism, 667 mg/ml; no pulmonary embolism, 161 mg/ml; P(0.001) and D-dimer/fibrinogen ratio (pulmonary embolism, 363; no pulmonary embolism, 0.460.4; P(0.001), but similar mean fibrinogen levels (pulmonary embolism, 3376184 mg/dl; no pulmonary embolism, 3846200 mg/dl; not significant). In patients who had pulmonary embolism, mean D-dimer level and D-dimer/fibrinogen ratio were greater in high-risk than non-high-risk patients. With Ddimer cutoff 0.35 mg/ml, sensitivity was high (100%) and specificity was low (27%) for pulmonary embolism. With D-dimer/fibrinogen ratio cutoff 0.13, sensitivity was high (100%) and specificity was low (37%) for pulmonary embolism. Conclusion: A D-dimer level ,0.35 mg/ml may exclude the diagnosis of pulmonary embolism. At a D-dimer cutoff 0.5 mg/ml and D-dimer/fibrinogen ratio cutoff 1.0, the D-dimer/fibrinogen ratio may have better specificity than D-dimer level in the diagnosis of pulmonary embolism, but the D-dimer/fibrinogen ratio may lack sufficient specificity in screening. © Acta Clinica Belgica 2014.