Observation of 219 patients with pulmonary tuberculosis was made to study the effect of acute respiratory viral infection (ARVI) on the course of the disease. The affected were divided into 2 groups: 136 subjects who had ARVI and 83 persons who did not have it during their stay at a hospital. Patients with infiltrative pulmonary tuberculosis, and young and middle-aged men were prevalent in both groups. It was found that ARVI promoted the aggravation of a specific process in the lungs in 19.1 per cent of the patients. Keeping in mind a large proportion of aggravations and low immunologic indices as a consequence of ARVI, 14 patients were put on kemantan. Study of the immune status of the patients who had ARVI and received kemantan demonstrated a significant increase in the formation of blasts and the concentration of T cells whose functional activity tended to rise. At the same time the above-mentioned indices remained intact or tended to drop in patients receiving no kemantan. The Soviet immunomodulator kemantan is recommended for a combined treatment of the pulmonary tuberculosis patients who had intercurrent viral infection to stimulate cellular immune defences and prevent an aggravation of the specific process.