Healthy adult male albino rats were subjected to inhalation of increasing doses of detergent (dioctyl sodium sulfo-succinate) aerosol ranging from 100 mg to 500 mg. Administration of 500 mg of detergent aerosol resulted in peribronchial and focal alveolar oedema in 3 out of 5 animals. The lungs of control animals which were subjected to inhalation of vehicle aerosol (ethanol and saline) did not show any abnormality. It is possible that pulmonary oedema observed in detergent aerosol inhalation may be due to the action of detergents on the surfactant system of the lung.