Lichen (Lecanora epibryon) collected from Arshany reservation at Idleb city was taken for screening antibacterial activity. Acetone was used as solvent for extraction of active compounds from lichen. The activity of extract was tested against three isolated infectious bacteria (Pseudomonas sp., Salmonella sp., Klebsiella sp.) by cytotoxicity assay using MTT test. Acetone extract of lichen showed antibacterial activity against all test organisms, but Salmonella sp. was highly susceptible to the extract even at low concentration.