The influence of the detergent dioctyl sodium sulfosuccinate on clearance from the lungs of inhaled technetium-99m-labelled dietylenetriamine pentaacetate (99mTc-DTPA) was studied in twelve rabbits. An aerosol of dioctyl sodium sulfosuccinate or its vehicle alone was administered for 5 min prior to aerosolized 99mTc-DTPA via a bag-in-bottle system. Time-activity curves were obtained from the right lung with a gamma camera. In rabbits given detergent, clearance of 99mTc-DTPA was significantly faster than in rabbits given vehicle alone. No changes were seen in arterial PO2 and compliance. Our data indicates that the transfer of 99mTc-DTPA from alveoli to blood can be accelerated by administration of the detergent dioctyl sodium sulfosuccinate without any dramatic change in surface tension. Clearance of 99mTc-DTPA may be a very sensitive indicator of altered surfactant function.