The antibacterial activity of different extracts of Quercus ilex bark (Fagaceae) was studied in vitro against seven reference strains of bacteria by using a disc-diffusion method and agar-dilution method. The ethyl acetate extract (QE), n-butanol extract (QB) and final aqueous layer (QA) were effective against all bacterial strains tested at MICs ranging from 128 to 512 μg/ml. The n-hexane extract (QH) and dichloromethane extract (QD) showed no activity.