After half a century of clinical experience and research, management of pulmonary arterial hypertension remains a challenge. Currently, data to support the use of standard therapies for pulmonary arterial hypertension (oxygen supplementation, diuretics, digoxin, anticoagulation, and calcium channel blockers) are mostly retrospective, uncontrolled prospective, or derived from other diseases with similar but not identical manifestations. In the absence of any further prospective, controlled studies, it is reasonable to use these therapies when they are tolerated. When these therapies are poorly tolerated, however, the threshold for discontinuation should be low.