The authors examined biochemically and histochemically the activity of alkaline phosphatase and adenosinetriphosphatase in lymph nodules of experimental animals, living under the conditions of continuous noise action (3 and 5 months) at a level of 95 decibels A for 3 hours daily in the morning. There were phase changes in the activity of the examined enzymes, which revealed considerable stability even after stopping the contact of the organism with noise factor. The manifested inhibition of the activity of alkaline phosphatase and partly of adenosinetriphosphatase suggested that the cells of lymph tissue revealed disturbances in the metabolic processes, which caused exhaustion of their protective function.