The diagnostic approach to pulmonary embolism can be divided in several consecutive steps. First of all, the clinician must identify the patients with potential pulmonary embolism based on clinical presentation and the presence or absence of personal risk factors. Further investigations can then be guided by the use of a clinical probability score. The revised Geneva score and the Wells score are the most validated tools. They are reliable in stratifying patients into low, intermediate, and high-risk categories. When clinical probability is low or intermediate, the dosage of d-dimers is helpful. A negative result excludes pulmonary embolism with a very high negative predictive value, close to 100%. When positive, a multidetector thoracic CT will confirm or exclude the diagnosis. The utility of a lower-limb venous ultrasound is very low, and its use is therefore no longer recommended.