Pulmonary hypertension is a state of increased blood pressure in pulmonary circulation. PH occurs in many different etiopathogenic ways and is a complication of many different pathological states. The World Health Organization has classified PH into five different categories based on their pathogenesis: pulmonary arterial hypertension, pulmonary hypertension associated with left heart disease, pulmonary hypertension associated with hypoxia, thromboembolic pulmonary hypertension (CTEPH) and pulmonary hypertension of unknown origin or due to multifactorial causes. The clinical presentation varies according to the primary cause and disease progression. The first symptom is progressive dyspnea. In patients with pulmonary hypertension associated with left heart disease there can be signs of left heart failure. In other types of PH there can be signs of right heart failure. The clinical diagnosis can be established based on medical history, physical examination, and the results of various diagnostic tests. These include laboratory findings, EKG, CT, MRI, scintigraphy, right heart catheterization, and others. Treatment is symptomatic, only thromboembolic pulmonary hypertension can be treated etiologically. The gold standard for treating such patients is pulmonary endarterectomy, and patients who don't meet the criteria for the procedure can have a pulmonary artery balloon angioplasty performed instead. Other types of pulmonary hypertension are treated with drugs from five different categories for lowering pulmonary blood pressure.