Continuous negative pressure (CNP) around the chest-wall and lower parts of the body was used to treat progressively alveolar disease. Therapy with CNP produced a substantial increase in arterial oxygen tension that was sustained and permitted a decrease in oxygen requirements to 40% within 24 hours. There were concomitant decreases in intrapulmonary right-to-left shunt and respiratory frequency. During CNP therapy, no adverse effects on heart rate or blood pressure were detected.