Tn5 from E.coli 1830,WA803 and SM10 was introduced by conjugation mating into cells of Xanthomonas campestris pv.oryzae JXO Ⅲ.The conjugation frequences ranged from 0.20×10^-5 to 0.40×10^-7 conjugants per recipient cell.The southern blot analysis of total DNA of randomly chosen conjugants with Tn5-containing plasmid(pJB4Jl:Tn5) as the ³²p-labelled probe,showed pJB4Jl::Tn5 hybridized only with the DNA of Tn5-induced mutants,not with that of wildtype strain JXO Ⅲ.