The criteria of differential administration of thymalin in the combined management of patients with destructive pulmonary tuberculosis were defined on the basis of immunologic studies. A ++clinico-roentgenologic and immunologic evaluation of in-patient treatment of 60 cases demonstrated that a differential administration of thymalin in combination with chemotherapeutic drugs greatly shortened the stay at a hospital and increased the efficacy of treatment. Besides, more evident normalizing influence of the proposed option of therapy on the recovery of the immune system links is noted.