Pulmonary hypertension (PH) is a serious disease with a poor prognosis. Pulmonary arterial hypertension (PAH) is distinguished from other forms of PHT. The leading symptom is exertional dyspnea. Patients with chronic severe PAH commonly die of right heart failure. PH has a complex heterogeneous aetiology, and precapillary forms are distinguished from postcapillary PH. A number of pathogenetically important signaling pathways such as the endothelin, nitric oxide and prostacyclin pathways have been identified, which constitute the target of the currently approved treatment options. Transthoracic echocardiography is the most important noninvasive diagnostic method. In addition, 6-min walking distance and measurement of serum markers, such as brain natriuretic peptide (BNP), are diagnostically useful and of prognostic significance.