Use of multi-plant extracts against infectious diseases is increasing in rural Tanzania. The study evaluated this ethnomedicinal practice by using mixed root extracts of Carisa edulis
, Ximenia caffra
, Harrisonia abyssinica
and Euclea natalensis
against single extracts of the same plants. Disc diffusion assay and Tube dilution techniques were used to compare bioactivity of plant extracts in-vitro
. The ANOVA test indicated significant difference (P < 0.05) between these extracts types. Multi-plant extracts had inhibition zones of up to 26mm as compared to 14mm for single extracts. Minimum Inhibitory Concentration for multi-plant extract was 8.3µg/ml against 69µg/ml for single extracts. Multi-plant extracts inhibited all the five test bacterial species while single extracts inhibited three species. Eight out of ten multi-plant extracts (80%) were bactericidal while only two out of four single extracts (50%) were bactericidal. Generally, multi-plant extracts were more superior over single plant extracts and could be developed into more potent antibiotics against resistant pathogens.