During a recent one-year period, 44 clinical centers in the United States saw 2,539 patients with diagnoses of pulmonary embolism as supported by high probability lung scans and/or positive pulmonary angiograms. In developing proposals for a clinical trial of Thrombolysis in Pulmonary Embolism (TIPE), investigators in the 44 clinical centers reviewed the 2,539 patients' medical charts for contraindications to thrombolytic therapy. Overall, 1,345 (53.5%) patients surveyed in the TIPE clinical centers would have been acceptable for treatment with thrombolytic therapy, a proportion higher than generally anticipated. Risks of major blood loss were the most frequent contraindications to thrombolytic therapy and were found in 838 (33.3%) patients. Risks to the CNS were found to contraindicate thrombolytic therapy in 453 (17.9%) patients. Risks of bleeding into special compartments were found to contraindicate thrombolytic therapy in 76 (3.0%) patients. Pulmonary embolism is underdiagnosed in most clinical settings, and even more patients than found in the TIPE survey could benefit from appropriate diagnosis and treatment. The question remains as to whether pulmonary embolism patients will benefit from thrombolytic therapy. Only a randomized clinical trial will provide a satisfactory answer.