Findings of immunologic observation of 35 subjects included into Group III of dispensary observation before and after antirecurring treatment with isoniazid and isoniazid in combination with ethymisole are presented. The findings indicate there is inhibition of immune cellular reactions in the above subjects (lower levels of T-suppressors and T-helpers and increased content of O-cells). Unfavorable changes in men are aggravated by suppressing antibody production; higher phagocytic blood activity is also detected. Thus, the antirecurring treatment promoted the normalization of immune reactions.