In experimental rheumatoid arthritis, certain indices for local defence of the lung were studied together with effects on these of preparations of vitamin E and thymalin. Noted in experimental rheumatoid arthritis are manifest changes in quantitative indices for cellular population of the bronchoalveolar space and disturbances in humoral mechanisms of defence of the lungs. The drugs employed for the treatment of the affliction have a positive effect on quantitative indices for the cell population of the lung local defence factors. But no significant effects could be demonstrated of thymalin on humoral factors of defence of the lungs. Unlike thymalin, tocopheroli acetas is noted to augment the secretion of lysozyme, to decrease the activity of phospholipase A2, to improve the surface-active properties of the lung surfactant. It is suggested that its antioxidant, membrane-stabilizing action may be responsible for the positive effect on indices for local defence of the lung.