The current study aimed to evaluate the antimicrobial properties of the methanolic extract of lichen thalli of Plastismatia glauca against some referenced bacterial and yeast strains. Disc diffusion test, minimum inhibitory (MIC) and minimum bactericidal (MBC) or minimum fungicidal (MFC) tests were carried out to evaluate the antimicrobial activity of lichen. All tested microorganisms exhibited varying degrees of susceptibility ranging from 18.5±1.0 to 11.0±0.0 mm zone of inhibition. It also showed high antifungal activity against the yeast Candida albicans (22.5±0.5 mm). The MIC, MBC and MFC were promising, with values as low as 3.125 to 12.5 mg/ml for MIC and 6.25 to 12.5 mg/ml for MBC and MFC. Accordingly, this lichen could be considered as a source of potential antimicrobial agents.