Abstract:Four-leaf seedlings of tobacco were used to study the resistance to tobacco mosaic virus (TMV). After the seedlings were sprayed with 1 mg ml-1 methyl jasmonate (MJ) once a day for 3 days, then TMV was inoculated to the leaves. Among three tobacco varieties, brazil tobacco (BX) showed lower disease index than the other two (GH55 and K326). Endochitinase, β1,3-Glucanase, superoxide dismutase (SOD) and lipoxigenase activities increased in MJ-treated BX tobacco seedlings. It is suggested that MJ plays an important role in the increase of SOD and in the resistance of BX tobacoo against TMV.