The repair processes in pulmonary tissue and granuloma in experimental tuberculosis were studied electron-microscopically and histochemically. At the beginning of inflammation they manifest at the ultrastructural level in aerohematic barrier cells. The period of granuloma formation is characterized by cell hypertrophy, particularly of type II alveolocytes, intensive macrophagal reaction, and increased functional activity of more and more cells. Ultrastructural and functional differences in epithelioid and multinuclear giant cells are revealed. A progressive course of tuberculosis involves decompensation of the compensatory and repair processes. Contrary to this, during chemotherapy of tuberculosis repair reactions predominate, resolution of inflammatory changes is in progress, cell populations in the granuloma change, and it is separated from the adjacent pulmonary tissue.