This clinical policy focuses on critical issues in the evaluation and management of patients with signs or symptoms of pulmonary embolism (PE). A MEDLINE search for clinical trials published from January 1995 through April 2001 was performed using the key words "pulmonary embolus" with limits of "clinical investigations" and "clinical policies." Subcommittee members and expert peer reviewers also supplied articles with direct bearing on the policy. This policy focuses on 2 major areas of current interest and/or controversy: (1) diagnostic: utility of D -dimer, ventilation-perfusion scanning, and spiral computed tomography angiogram in the evaluation of PE; and (2) therapeutic: indications for fibrinolytic therapy. Recommendations for patient management are provided for each 1 of these topics based on strength of evidence (Level A, B, or C). Level A recommendations represent patient management principles that reflect a high degree of clinical certainty; Level B recommendations represent patient management principles that reflect moderate clinical certainty; and Level C recommendations represent other patient management strategies based on preliminary, inconclusive, or conflicting evidence, or based on panel consensus. This guideline is intended for physicians working in emergency departments or chest pain evaluation units.