Background and Aim: Irvingia gabonensis and Irvingia wombolu seeds and stem barks are used in herbal medicine. The stem barks are used against bacterial infections in Nigeria. The present work is aimed at evaluation of the antibacterial activity of the stem barks of Irvingia gabonensis and Irvingia wombolu grown in Nigeria and also to ascertain which of the wombolu and gabonensis species has greater antibacterial activity. Materials and methods: Each of the stem barks was air-dried for one week and ground into powdered form. This was separately extracted with ethanol and water, using Soxhlet extraction apparatus, to give the ethanol and water extracts respectively. Antimicrobial susceptibility of each of these extracts was carried out using agar well diffusion method while minimum inhibitory concentration was determined through broth dilution method. Results: The test microorganisms, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae are susceptible to all the extracts. The wombolu species has much stronger antibacterial activity than the gabonensis species. The aqueous extract in each case has greater activity than its corresponding ethanol extract. Conclusion: Irvingia gabonensis and Irvingia wombolu stem bark extracts have strong antibacterial activity against both gram negative and positive bacteria.