The in vitro antibacterial activity of Silene Succulent leaves extracts of water, ethanol, methanol and chloroform against five species of clinical pathogenic bacteria was assessed. The antibacterial activity was tested by the agar well diffusion method. The organic extracts showed variable results for the tested bacterial species, the most effective organic extract was chloroform extract and exhibited an inhibitory effect against four bacterial species at all concentrations used Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella sp. and Escherichia coli, while the aqueous extract was effective against two bacterial species at all concentrations used S.aureus and E.coli. The organic extracts were the most effective extracts and showed bacteriostatic activities against the highly susceptible species of pathogenic bacteria S. aureus and P. aeruginosa with MIC ranged from 12.5 to 25 mg/ml except P. aeruginosa which was less sensitive to ethanol extract and its MIC reached to 50 mg/ml. These plant extracts which proved to be potentially effective can be used as natural alternative preventives to control diseases caused by this bacterial species and avoiding health hazards of chemically antimicrobial agent applications.

Key words: Silene succulent Forsk, antibacterial activity, agar well diffusion method, MIC.