The antimicrobial activities of ethyl acetate and methanol extracts of Satureja hortensis L. were studied. These extracts were tested in vitro against 10 bacterial species, 4 yeasts species and strains by the disc diffusion method. The results indicated that the methanol extract of S. hortensis is more effective against tested microorganisms than ethyl acetate. While ethyl acetate extract showed inhibition effect against Pseudomonas aeruginosa (ATCC 27853) and Bacillus subtilis (RSHI), methanol extract affected Bacillus subtilis (RSHI), Escherichia coli (ATCC 25922), Shigella (RSHI), Staphylococcus aureus (ATCC 29213) and Pseudomonas aeruginosa (ATCC 27853). The cells of microorganisms treated with plant extracts and normal microorganism cells were observed by scanning electron microscope. It was apparent that cells after treated with S. hortensis are damaged