Five isolates of Ralstonia solanacearum were isolated from a naturally wilted root of tomato plants grown in Assiut governorate. The antibacterial activity of extract of Datura, Garlic and Nerium were tested in controlling R. solanacearum in vitro and in vivo. Garlic exhibited the strongest antibacterial activity against bacterial wilt in vitro and in vivo followed by Datura and then Nerium. Cold water extract of these plant species were more effective than hot water extract in the development of the disease in vivo. In greenhouse experiments, the application of the tested plant extract to soil at the time of inoculation, two days before inoculation and two days after inoculation the pathogen, significantly reduced the disease index of wilt on Super Marmande tomato cultivars. The application of plant extracts at the same time of inoculation resulted in the highest reduction of disease index.