Rapidly progressive heart failure, in part related to severe pulmonary hypertension, developed in a patient with biopsy-proved Whipple's disease. The patient's pulmonary hypertension progressed despite antibiotic therapy and histologic remission of his intestinal disease. The combination of oral nifedipine and low-flow continuous oxygen led to both short- and long-term increases of at least 2 liters per minute in cardiac output and reductions of more than 10 mm Hg in mean pulmonary artery pressure. Accompanying these hemodynamic changes was an improvement of more than 10 percent in right ventricular ejection fraction. The relationship between this patient's pulmonary hypertension and his Whipple's disease is not known.