The risk of development of bronchi and lungs cancer (BLC) in workers, exposed to dust containing SiO 2 , is characterized by a long-term course of pneumoconiosis (PC), chronic bronchitis (CB), chronic obstructive lung disease (COLD). To morphofunctional signs, which contribute to high risk of BLC development in patients, the occurrence and progress of the following disorders in patients with PC can be referred: diffusive pneumosclerosis, emphysema, interstitial (s-type) and nodular (p-nodular) changes, addition of the tuberculosis process and development of the mixed type of lungs insufficiency; in patients with CB and COLD-development of the diffusive pneumosclerosis, lungs insufficiency of mixed or obstructive types. A three-step system of actions has been proposed, directed at prophylaxis and early diagnostics of BLC in patients with PC, CB and COLD.