This paper reports a new transgenic tobacco line NC89 resistant to both tobaccomosaic virus(TMV)and cucumber mosaic virus(CMV).It deals with the details of field experi-ments of the whole process of segregation and selection of the progenies of transgenic plant popu-lation.By using the gene transfer technics,some transgenic plants resistant to mosaic disease froma flue-cured tobacco cultivar NC89 were obtained in green house in 1989.Thereafter,throughfield inoculation and selection from the 2nd and 3rd generations,a homozygous line resistant toboth viruses and with good qualities was bred out.The inheretant stability of the resistance of thenew line was confirmed through the 4th to 6th generations.In 1992,the transgenic resistant linewas planted about 7000 hectares in Henan province.The relative effect of controlling mosaic dis-eases of tobacco was 50—70%.The out-put value increased 30—50% per unit area.This is a newexample of growing a transgenic virus-resistant Plant in large scale in China. This paper reports a new transgenic tobacco line NC89 resistant to both tobaccomvirus (TMV) and cucumber mosaic virus (CMV) .It deals with the details of field experi-ments of the whole process of segregation and selection of the progenies of transgenic plant popu -lation.By using the gene transfer technics, some transgenic plants resistant to mosaic disease froma flue-cured tobacco cultivar NC89 were obtained in green house in 1989. Hereafter, throughfield inoculation and selection from the 2nd and 3rd generations, a homozygous line resistant toboth viruses and with good qualities was bred out. Inheretant stability of the resistance of the new line was confirmed through the 4th to 6th generations. In 1992, the transgenic resistant linewas planted about 7000 hectares in Henan province. The relative effect of controlling mosaic dis- eases of tobacco was 50-70%. The out-put value increased 30-50% per unit area. This is a new sample of growing a transgenic virus-resistant plant in large sca le in China.