Pulmonary embolism (PE) represents the third more frequent cardiovascular disease following the acute coronary artery disease and stroke. The most important predisposing clinical condition for PE is represented by the deep-vein thrombosis. The clinical diagnosis of PE has a very low accuracy; so the clinical suspect has to be necessarily directed towards the performance of diagnostic procedures. Among the most used procedures, the echocardiography has a diagnostic role but also a prognostic one. Moreover, it offers precious informations useful to perform the most suitable treatment. The echocardiography features which suggest the presence of pulmonary embolism are: right ventricle and atrium dilatation, right ventricular hypokinesia, systolic flattening of the interventricular septum, tricuspid regurgitation, pulmonary artery dilatation, disappearance or reduction of the inspiratory collapse of the inferior vena cava and presence of eventual embolic sources. According to the involvement degree of right ventricular function, it is generally possible to identify a different survival. The subgroup of patients with moderate or severe right ventricular dysfunction shows a high in hospital and within 1 year death rate. For this reason the right ventricular dysfunction degree together with the hemodynamic stability, are the most important parameters in the therapeutic choice. If there is no right ventricular dysfunction a treatment with heparin is indicated. In presence of right ventricular dysfunction and hemodynamic instability, the thrombolytic treatment is necessary. If the patient is hemodynamically stable, a transesophageal echocardiography is recommended; in case of central thrombosis the thrombolytic therapy or surgery are needed, while if no embolic material is shown the heparin treatment is advisable.