Two patients with von Recklinghausen disease (neurofibromatosis type 1) were admitted to the hospital because of progressive heart failure. Both patients had prominent pulmonary hypertension revealed on cardiac catheterization. A lung perfusion scan did not show any gross defect. There were no underlying causes of pulmonary hypertension in either patient, such as chronic lung disease, congenital or acquired heart disease, deep vein thrombosis, or systemic hypercoagulable states. There may be an unrecognized association between von Recklinghausen disease and pulmonary hypertension.