The crude extracts of Jatropha tanjorensis were investigated with the aim of determining the antibacterial activity, qualitative and quantitative properties, the best solvent used for extraction, the most active ingredients and the organism that is most susceptible to them. Ethanol, petroleum ether and water (warm) were used as solvents. Agar well diffusion method was used for the susceptibility of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa to the extracts, with streptomycin as positive control and sterile water as negative control. Ethanol extracts of the plant showed most activities, whereas petroleum ether and water (warm) extracts had no activity on the test organisms. The ethanol extracts of Jatropha tanjorensis leaf inhibited the growth of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa with inhibition zone of 6.0±0.04 mm, 5.5±0.70 mm and 7.5±0.70 mm respectively. This study reveals that the ethanol extracts of Jatropha tanjorensis have antimicrobial effect on three test pathogens, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa.