Pulmonary embolism is the third cause of mortality by cardiovascular disease after coronary artery disease and stroke, and its incidence is around 1/1000 per year. During the last two decades, many different non-invasive diagnostic tests have been developed and validated. For hemodynamically stable outpatients, the diagnosis of acute pulmonary embolism mainly rests on the sequential use of clinical assessment, D-dimer measurement and multidetector CT. In patients with a contraindication to CT, lower limb venous ultrasonography and ventilation-perfusion scintigraphy remain valid options. Massive pulmonary embolism is a distinct clinical entity with a specific diagnostic approach. In unstable patients with suspected pulmonary embolism, echocardiography should be the initial test.