We report 2 patients with refractory acute pulmonary hypertension. In both, a central venous infusion of adenosine into the circulation effectively lowered pulmonary arterial pressure when standard treatment measures had failed, and reversed the clinical state of shock by achieving pulmonary vasodilatation. We conclude that adenosine may help lower pulmonary arterial pressure without lowering systemic arterial pressure in the setting of acute pulmonary hypertension when standard measures have failed.