The study was carried out to ascertain the phytochemical constituents as well as the antibacterial activity of Methanolic, Ethanolic and Aqueous extracts of stem and root bark of Strychnos innocua on Escherichia coli and Salmonella species. Plant parts were successively extracted using cold maceration method and the phytochemical constituents were determined using method of Trease and Evans. Agar well diffusion method was used in determining the antibacterial activity while broth dilution method was employed in the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC). The inhibitions of the test organisms were measured by measuring the diameter of the zone of inhibition. Column chromatography was used in fractionating the extract with the best antibacterial activity. The phytochemical screening revealed the presence of carbohydrate, glycosides, anthraquinones, cardiac glycosides, saponins, steroids and triterpens, flavonoids, tannins and alkaloids in the plant parts used. The extracts showed good inhibitory activities against Escherichia coli and Salmonella species. The extracts gave different MICs against the test organisms using the double-fold dilution method, with concentrations ranging between 37.5 to 300mg/ml. The ethanolic extract of the stem bark was the most potent against the test bacteria with a minimum inhibitory concentration (MIC) of 37.5mg/ml for Escherichia coli and 75mg/ml for Salmonella species. The MBC assay revealed that most of the extracts were bactericidal at the concentrations of 75mg/ml for Escherichia coli and 150mg/ml for Salmonella species. The study revealed that subfractions of the ethanol extract of the stem bark had antibacterial activity with hexane/chloroform subfraction having best activity.