Ultrathin bronchofiberscope(Olympus BF-1.8T) was applied to the observation of theperipheral airways of total 87 cases,including 73 cases of quartz-exposed and asbestos-exposed workers with/without pneumoconiosis(exposure groups),and 14 cases of controls.The changes of peripheral airways in exposure group of non-smokers was found,mainly to bepigmentation,elevation,irregularity and lustlessness on the surface of the bronchiole walls,and predominately stenosis and ectasis of the lumen.The detectable rate was higher inperipheral airways than in central airways.Some changes existed in early stage and some had atendency of increasing detectable rate with category progressing.Some factors such assmoking could influence the results of analysis. Ultrathin bronchofiberscope (Olympus BF-1.8T) was applied to the observation of the peripheral airways of total 87 cases, including 73 cases of quartz-exposed and asbestos-exposed workers with / without pneumoconiosis (exposure groups), and 14 cases of controls. changes of peripheral airways in exposure group of non-smokers was found, mainly to bepigmentation, elevation, irregularity and lustlessness on the surface of the bronchiole walls, and predominately stenosis and ectasis of the lumen. detectable rate was higher inperipheral airways than in central airways.Some changes existed in early stage and some had atendency of increasing detectable rate with category progressing.Some factors such assmoking could influence the results of analysis.