The specific features of the course of chronic occupational bronchitis (OCB) and its relationships with occupational chronic obstructive pulmonary disease (OCOPD) have not been adequately investigated in the clinic of occupational pathology. The aim of the study was to study risk factors, clinical features and prognosis of chronic non-obstructive bronchitis. 222 patients (metal workers) with OCB and OCOPD were randomly selected for the study. The medical histories of diseases were studied from the initial diagnosis to the present status (in average the period of 10 years).Patients were divided into three groups: with the initial diagnosis of OCOPD (1), with the initial diagnosis of OCB, but transformed to OCOPD (2) and the patients with the initial diagnosis of OCB (3). Patients were divided into three groups: those initially diagnosed with COPD PE made up group No. 1, those initially diagnosed with CKD PE who did not show signs of COPD PE during the annual examination made up group No. 2, and those initially diagnosed with CKD PE who showed signs of COPD PE during the dynamic examination made up group No. 3. All groups showed a decrease in spirometry parameters. FEV1 was statistically significantly decreased by 12% in group 1, by 13% in the second group and by 27% in the third group. When analyzing modified Typhno index (MTI) values in group 3, there was a statistically significant decrease in MTI from baseline by 21% (p=0.002, Z = 2.9, Wilcoxon test). In 52 people out of 156 (or 34.6%) with the initial diagnosis of OCB, a manifestation of OCOPD occurred during the observation period. Two phenotypes of chronic bronchitis were distinguished: with favorable and unfavorable prognoses. Patients with OCB, after establishing a professional diagnosis, should be recommended to rational employment out of exposure to industrial aerosols, due to the high risk of disease progression.Funding. The study had no funding.Conflict of interests. The authors declare no conflict of interests.