Pulmonary hypertension (PH) is a devastating disease that - if untreated - is characterized by a poor prognosis. According to the current classification (Venice, 2003), pulmonary arterial hypertension (PAH) is distinguished from other forms of PH. Recent advances in drug therapy have led to a dramatic improvement of medical care particularly in patients with PAH. Hence, early establishment of the diagnosis appears increasingly important. This review article gives an overview on the definition, classification, pathophysiology, and clinical presentation of various forms of PH. Furthermore, it summarizes the recommended diagnostic work-up and the current treatment options particularly in PAH, with special emphasis on prostanoids, endothelin receptor antagonists (ERAs), and phosphopdiesterase type 5 (PDE5) inhibitors such as sildenafil. Finally, novel developments are being discussed which currently represent an exciting field of research.