Experiments were conducted on 128 male rats kept on a retinol-deprived diet during 12-14 weeks, that resulted in vitamin A deficiency. The content of phospholipids, total lipids, proteins and the activity of esterase, glutamate dehydrogenase, catalase, glutathione-S-transferase, aldehyde dehydrogenase and aldehyde oxidase were assayed in the bronchoalveolar lavage fluid, in homogenates and microsomes of the lungs. The content of phospholipids in the bronchoalveolar lavage fluid was reduced up to 63.9%, as compared to that in the control rats, while the protein content was unchanged. The levels of phospholipids, total lipids and protein rose in the homogenates and microsomes of the lungs. Esterase activity decreased up to 38.6% of the control level, catalase--up to 73.2%, glutamate dehydrogenase--up to 79%. There was a tendency to decrease in glutathione-S-transferase activity, while aldehyde dehydrogenase and aldehyde oxidase activities remained unchanged. It is suggested that the disorders in the enzymatic activity and lipid content in the surfactant can be responsible for the changes in the xenobiotic biotransformation and for the rise in xenobiotic toxicity.