Hemodynamic studies of the response of the pulmonary vasculature to vasodilator drugs were performed in 3 patients with systemic lupus and pulmonary hypertension. In one patient isoproterenol infusion produced a reduction in total pulmonary resistance, but increased pulmonary blood flow and pulmonary artery pressure. No significant change in pulmonary artery pressure or resistance was noted with nifedipine in any of the patients. One woman with associated pulmonary infiltrates improved symptomatically with high dose steroids.