Abstract: This paper emphasizes on the correlation between the highoccurring occupational lung cancer and potential mutagenicity of five kinds of Yunnan tin ore powder and four kinds of metallic compound.After treatment of rats by administration through trachea with these ore powder and compounds,the cytological preparations are made at various intervals for observing the effects of these ore powder and metallic compound on the frequencies of micronucleus and karyorrhexis of rat bone marrow cells and lung macrophages.The results are as following:1.All the ore powder and two kinds of metallic compound SnO2 and Fe2O3 can induce micronuclei and karyorrhexis in bone marrow cells.On first and 10th day,the frequency of karyorrhexis is higher than that of micronuclei and differs significantly from that of the control and vice versa on 20th and 30th day.2.All of the ore powder and metallic compound can also induce micronuclei and karyorrhexis in lung macrophages,and on 10th and 20th day,the frequency of karyorrhexis is as the same as that in bone marrow cells.