The antimicrobial activity of 24 strains of lactic acid bacteria (LAB) isolated from kefir, cheese, and kashar cheese samples on various Gram-positive and Gram-negative food-borne pathogens and contaminating bacteria was determined by an agar diffusion method. The highest antimicrobial activity of strains was 27.5 mm against Micrococcus flavus, whereas the lowest antimicrobial activity of strains was 4.5 mm against Staphylococcus aureus. Also, these strains were tested for their antibiotic resistance. All strains were resistant to vancomycin and gentamicin. Most strains were resistant to amoxicillin (88%), lincomicin (72%) and erythromycin (68%) and susceptible to tetracycline (64%) and ampicillin (56%). Antimicrobial activity and antibiotic susceptibility of lactic acid bacteria are important factors in the protection of fermented dairy products.