Changes in the content of lysozyme and copper were studied in the blood serum of rats in four time intervals (1, 2, 12, and 24 weeks) after administration of 50 mg TiO2, Sio2 or coal dust and the copper content was also studied 12 weeks after administration of 3 industrial dusts. The obtained results were supplemented by histopathological examinations and in the 12-week interval by the determination of the lung wet weight. The lysozyme content was statistically significantly increased compared to controls practically over the whole time course with differences in the level of the response to SiO2 in comparison with the response to TiO2 and coal. With the exception of the first interval, the serum copper level was statistically significantly increased only after quartz dust administration. The obtained results were compared with literary data and findings reported from clinical practice.