The study was done to evaluate antibacterial activity in Senna didymobotrya roots methanolic-aqua extract and the selected fractions against selected pathogenic bacterial organisms. The aqueous fraction of S. didymobotrya root inhibited B.cereus giving the best results followed by Salmonella typhi, P.vulgaris, S. liquefaciens and E. coli respectively. There was no inhibition for E. aerogenes. Analysis of variance (ANOVA) showed that the organisms were significantly different in the zones of inhibition (p< 0.05). The ethyl acetate fraction of S. didymobotrya root extract inhibited B. cereus the best followed by, Salmonella typhi, P.vulgaris, S. liquefaciens and E. coli respectively(Table 1). The extract fraction did not inhibit E. aerogenes. The crude extract of S. didymobotrya root inhibited all the organisms, with the best zone of inhibition been that of Bacillus cereus (29.67±0.882), followed by P.vulgaris (16.67±0.667), Salmonella typhi (15.67±0.667), E. coli (13.33± 0.667), E. aerogenes (12.00±0.000) and Serratia liquefaciens (11.33±0.667). These results have shown that S. didymobotrya extract show significant activity against all the organisms tested. The inhibition of the plant roots extract to the growth of all the organisms greatly depicts the plant roots to have great potency towards the treatment of diseases caused by the organisms. The antibacterial activity of the plant roots is due to the presence of important phytochemicals as observed in previous studies. Further research needs to be done in order to isolate the active compounds, their structural elucidation, mode of action and their effect in the in vivo environment.