Recent years have witnessed a significant increase in the knowledge about the pathophysiology of pulmonary arterial hypertension (PAH) and the availability of multiple drugs specifically aimed at pulmonary circulation. Although most of this is related to the idiopathic form of PAH, this development has also turned attention to other forms of pulmonary hypertension such as schistosomiasis-associated PAH (Sch-PAH), portopulmonary hypertension (POPH), and hemolysis-associated pulmonary hypertension. The importance of these different forms of pulmonary hypertension spans their epidemiology and the multiple pathophysiological mechanisms associated with their development and complications. Taken together, Sch-PAH and hemolysis-associated pulmonary hypertension may represent the most prevalent forms of PAH worldwide. Portopulmonary hypertension is particularly important if the morbidity and mortality that it adds to patients with liver disease is considered. Although clear progress has been reached in these various forms of PAH, there are many different aspects yet to be addressed that may contribute to the basis of specific treatment applied to these subgroups of patients.