We placed BcGR1, a Chinese cabbage (Brassica campestris var. Pekinensis) gene that encodes cytosolic glutathione reductase (GR), under the control of the cauliflower mosaic virus (CaMV) 35S promoter. This gene was then introduced into tobacco plants via Agrobacterium-mediated transformation. Segregation and northern analyses of the transgenic plants revealed no relationship between the copy number of the introduced gene and levels of BcGR1 transcript. Homozygous lines containing BcGR1 were generated and tested for their acquisition of increased tolerance to oxidative stress. When 10-d-old transgenic tobacco seedlings were treated with 5 to 20 $mu$M methyl viologen (MV), they showed significantly increased tolerance compared with the wild-type seedlings. The most drastic difference was observed at a concentration of 10 $mu$M MV. In addition, when leaf discs were subjected to MV, the transgenic plants were less damaged than the wild types with regard to their electrical conductivity and chlorophyll content.