Transthoracic echocardiography is advocated by some as a useful diagnostic test for patients with suspected pulmonary embolism (PE), but its diagnostic accuracy is unknown. Recently, the sensitivity and specificity of transthoracic echocardiography in the diagnosis of PE was determined prospectively in unselected patients using pulmonary angiography as a reference diagnostic standard. Echocardiographic criteria for diagnosing PE included the presence of any two of three abnormalities: right ventricular (RV) end-diastolic diameter > 27 mm (without RV wall hypertrophy), tricuspid regurgitation velocity > 2.7 m/s, or RV hypokinesis. These echocardiographic diagnostic criteria for PE yielded a sensitivity of 56% and a specificity of 90%. Because of its inherent poor sensitivity, transthoracic echocardiography should not be used as a routine test to screen patients for suspected PE.