Reactive airway disease has only rarely been associated with pulmonary hypertension. We treated two patients with congenital heart disease and asthma who had increased pulmonary arterial pressure at cardiac catheterization. Pulmonary hypertension could not be explained solely by the cardiac lesion, nor by respiratory mechanical factors, as the patients did not have wheezing during the catheterization study. After long-term treatment with bronchodilators, corticosteroids, and oxygen, and coincident with improvement in the airway disease, there was catheterization-proved diminution of pulmonary hypertension. Whether asthma and pulmonary hypertension were causally linked is unknown, but further work seems indicated to elucidate the relationship between bronchoconstriction and pulmonary vasoconstriction. Furthermore, aggressive management of even mild reactive airway disease may be warranted in patients with pulmonary hypertension, regardless of apparent cause.