The annual incidence of pulmonary embolism (PE) in western industrial nations is about 1 to 1.5 cases per 1,000 citizens. For the prognosis of the patients it is important to consider PE early as a differential diagnosis. The clinical disorders are non-specific and varied. The most frequent clinical signs of PE are dyspnoea, tachypnoea, tachycardia and chest pain. Diagnostic algorithms are available for the diagnosis of PE. There is a cardinal difference in diagnostic procedure between clinically stable and instable patients. The criteria for stability are mainly hemodynamic values. In hemodynamically instable patients echocardiography is the most important diagnostic tool. Therapeutical goals depend on the severity of PE and include hemodynamic stabilisation, prevention of the growth of the thrombus, recanalisation of pulmonal arterial vessels, removal of hypoxemia, and prophylaxis of recurrence. Anticoagulation is the only therapy of choice in stable patient of risk classification I. Interventions like thrombolysis and embolectomy are mainly indicated in hemodynamically instable patients.