Pulmonary embolism (PE) is a disturbance of the pulmonary circulation often with nonspecific signs and symptoms. It is very common (at population level 0.5–1 cases per 1 000 annually). If not diagnosed and treated promptly PE may prove to be fatal. The pretest probability of PE must be included in the differential diagnosis of all patients who present with chest pain and dyspnoea, particularly in those with coexisting risk factors. PE most commonly originates from lower limb deep vein thrombosis (DVT). DVT may be clinically asymptomatic.