In view of the manifold options for mono- and combination therapy that have now emerged for patients with pulmonary (arterial) hypertension (PH/PAH), controlled clinical trials can only provide part of the information needed for optimal management. In order to gather adequate data on PAH/PH treatment in routine clinical care, the ongoing COMPERA registry prospectively documents consecutive patients with newly initiated treatment of PAH/PAH since May 2007. The internet-based registry fulfills high quality standards through several measures (planned minimum centre contribution of at least 10 patients per year, automated plausibility checks of data at entry, queries, monitoring with source data verification in >50% of participating centers). It can be applied, among further purposes, for quality assurance: individual centers can confidentially compare their results with the combined outcome of other centers and the recommendations from guidelines. It is expected that the register contributes to optimization of specific drug therapy for PAH and PH.