The macrophageal elements (ME) of bronchoalveolar lavage were cytologically and electron microscopically studied in 11 patients with active pulmonary tuberculosis who took antituberculous drugs during 3-6 months, which did not yield a significant clinical effect (Group 1) and in 24 patients with the disease who received inhaled C-BL during chemotherapy (Group 2). The drug was administered in a dose of 20 mg by a nebulizer every second day during 4-9 weeks. In Group 1, the high levels of young biosynthesizing (32.08 +/- 0.10) and mature secreting (11.50 +/- 0.70) ME were combined with the lower counts of phagocytizing macrophages (11.50 +/- 0.90). In Group 2, the specific features depended on the duration of C-BL use and after 20-28 inhalations their composition tended to normalize: biosynthesizing (18.30 +/- 1.05), secreting (5.80 +/- 0.95), and phagocytizing (47.20 +/- 1.05). In 19 patients from Group 2, the therapeutic effect was clinically regarded as positive.