In Zaire, traditional healers use many local plants for the treatment of microbial disease. Out of the 827 plants which have been inventoried in the Kivu Province (Eastern Zaire), about 220 (26.6%) are considered to have antimicrobial potential. The seed powder of Mirabilis jalapa L. (Nyctaginaceae), an ornamental plant introduced into Zaire from Latin America, is used to cure externally infected wounds. The powder of the crushed seeds is rubbed on the wound. In Latin America, this plant is used in traditional medicine because of the purgative or emeticcathartic properties contained in its roots (Perrot, 1943). In Malagassy, it is used to treat inestinal pains. In South Africa, the roots are used as a purgative drug and it is reputed that the flowers of this plant at night exhale a strong odour which will stupefy or drive away mosquitoes. The roots contain oxymethylanthraquinone (Watt and BreyerBrandwijk, 1962). In the present study, the antibacterial activity of seed powder extracts are screened against some Gram-positive and Gram-negative bacteria respectively isolated from infected wounds and diarrhoeic feces.