The flower buds of Syzygium aromaticum (Cloves) are a well-known spice, prescriped for treatment from some microbial diseases since ancient civilizations and in traditional medicine today. In the currenrt investigation, the methanolic extract of cloves was tested against 4 Gram-positive bacteria , namely Bacillus cereus ATCC10876, Staphylococcus saprophyticus ATCC 43867, Enterococcus faecalis ATCC 29212 and Staphylococcus epidermidis ATCC 12228. In addition to 5 strains of Gram-negative bacteria , namely Proteus vulgaris ATCC 6380, Klebsiella pneumoniae ATCC 27736, Salmonella typhimurium ATCC 14028, Shigella flexneri ATCC 12022 and Escherichia coli ATCC 25922, using two diffusion methods (Cup-plate and disc diffusion methods), besides MIC and MBC testings. The extract showed noticable dose-dependant antibacterial activity against all tested bacterial strains with varied degrees, and there was no significant differences between the results of the cup-plate diffusion assay and the disc-diffusion assay. Moreover, MIC values were between 3.9 to 125 mg/ml, and MBC values ranged between 7.8 to 125 mg/ml, which was higher than the MIC’s, the MBC/MIC ratio indicating that the extract has a bactericidal attitude, which makes it suitable source for the formulation of new antibacterial drugs.