In pulmonary hypertension there is a discrepancy between the dramatic but unspecific clinical presentation and the remodeling of mostly only limited segments of the vascular compartment of pulmonary parenchyma. Clinical diagnosis relies for the most part on invasive procedures, such as right heart catheterization. Therefore, morphology can provide a reliable etiopathogenetic classification only in close cooperation with the clinical partner disciplines involved. Moreover, the histopathological approach requires intimate knowledge of the vascular anatomy of the lungs and assessment of the parenchyma to be able to diagnose pulmonary hypertension and differentiate between the various types.