The antibacterial activity of aqueous extracts and essential oils of twenty medicinal plants of Egypt were determined by the agar diffusion-method against three bacterial species, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis, isolated from colorectal cancer tissues and normal adjacent tissues. Aqueous extracts and essential oils showed significant antibacterial activity against all the bacterial species tested. The highest significant inhibition zone and percentage relevant to tetracycline (positive control) was found for marjoram, black cumin and peppermint essential oils against B. subtilis isolated from tumoral and normal tissues. Marjoram and basil showed significant antibacterial activity against E. coli. Meanwhile, thyme and rosemary showed significant inhibitory activity against P. aeruginosa. The data also suggested that the best aqueous extract was from Albizzia lebbeck, which inhibited the growth of all bacterial strains tested except for B. subtilis isolated from tumoral tissues.