Abstract: Tobacco mosaic virus (TMV)and cucumber mosaic virus (CMV)were detected in tobacco tissue by dot-immunoblots enzyme-linked immunosorbent assay (ELISA)and tissue blot-ELISA.1 000-dilution rabbit-antiTMV antibody could be used to detect purified TMV with limitation of 1.25ng/ml, and for TMV infected tobacco sap extracts with limitation of 1:2 560.500-dilution rabbit-anti-CMV antibody could be used to detect CMV infected tobacco sap extracts with limitation of 1:2 560.Detection of health tobacco sap extracts with dot-ELISA in low dilution exhilbited false positive results, high dilution could eliminate false positive phenomena.Dot-ELISA with rabbit-anti-TMV antibody in 1 000 dilution, rabbit-anti-CMV antibody in 500 dilution, tobacco sample sap extracts in 300 dilution and tissue blots were applied for detected TMV and CMV in mosaic tobacco sample collected from field in Qujing, Yunnan.The samples were detected by electrical microscopy in the same time.The results showed that dot-ELISA and tissue blot-ELISA performed well in detection of TMV and CMV in tobacco sample.The tissue blot-ELISA is more simple and sensitive than dot-ELISA, and suit for large amount samples routine detection.