Extracts of six ethnobotanically selected medicinal plants (Anredera cordifolia, Elaeodendron transvaalense, Elephantorrhiza burkei, Senna petersiana, Terminalia sericea and Rauvolfia caffra) used traditionally to treat sexually transmitted diseases (STD's) were investigated for antibacterial activity using the agar dilution method. Of the six collected, Terminalia sericea, Senna petersiana and Anredera cordifolia were also investigated for cytotoxicity. The phytochemical studies on Senna petersiana resulted in the isolation of luteolin, which also showed antimicrobial activity. Only the Senna petersiana extract and luteolin isolated from it were tested for antiviral activity and showed some activity at the highest non-toxic concentration of 24 and 500 microg/ml, respectively. The results of the antimicrobial screening support the ethnomedicinal uses of these plants to some extent.