Under general anaesthesia, therapeutic bronchopulmonary lavage was performed in two patients suffering from alveolar proteinosis. In one patient, difficulties were experienced during attempted lavage of the right lung. Fluid trapping occurred when saline was infused down the tracheal (right) lumen of a Carlen's double lumen endobronchial tube and also when a left Robertshaw tube was similarly used. Spillover of saline into the left lung occurred when a right Robertshaw was used. Efficient lavage of the right lung could only be performed after insertion of a White endobronchial tube. In the second patient, both lungs were washed without problem using a left Robertshaw tube after difficulty had been experienced with a Carlen's tube. In both cases venous admixture was least when the lavaged lung was filled with saline. Hypoxaemia increased as the lung was drained. Details of technique are discussed as are problems with double lumen endobronchial tubes used during the procedure.