1. This study investigated whether the reactive organohalogen gases perfluoroisobutene (PFIB) and phosgene, which cause death by overwhelming pulmonary oedema, affect the surfactant system or type II pneumocytes of rat lung. 2. The progression and type of pulmonary injury in Porton Wistar-derived rats was monitored over a 48 h period following exposure to either PFIB or phosgene (LCt30) by analyzing the inflammatory cells and protein in bronchoalveolar lavage fluid. Six rat lung phospholipids were measured by high-performance liquid chromatography, following solid phase extraction from lavage fluid. 3. Alterations in the cell population and lung permeability occurred following both gases, indicating that the injury was a permeability-type pulmonary oedema. Changes in the total amount of phospholipid and in the percentage composition of the surfactant were different for the two gases. PFIB produced increases in phosphatidylglycerol and phosphatidylcholine over the first hour, similar to that seen following air exposure, followed by substantial decreases in these phospholipids. Phosgene caused late increases in all phospholipids from 6 h post-exposure. 4. Differences in the response of the surfactant system to exposure to PFIB and phosgene suggest different mechanisms of action at the alveolar surface although the final injurious response is pulmonary oedema for both gases.