Background & Aim: Due to the prevalence of oral bacteria, their complications and increased microbial resistance and also recognition of the antibacterial properties of Polylophium involucratum, in this study, the antimicrobial properties of this plant essential oil were tested in different dilutions on oral bacteria at the Faculty of Microbiology of the Islamic Azad University of Lahijan in 2015. Experimental: In this study, the antibacterial properties of Polylophium involucratum essential oil at different concentrations of1: 6, 1: 12, 1: 24, 1: 48 and 1: 96, were tested on oral bacteria including Streptococcus mutans and Streptococcus sanguinis with disk fusion method. Results: According to results, the Polylophium involucratum essential oil had a greater antibacterial effect on the Streptococcus sanguinis than the Streptococcus mutans. The highest inhibition zone values were observed against the Streptococcus sanguinis, ranging from 18mm to 27mm. Also, the antibacterial properties of polylophium involucratum essential oil were higher than other chemical drugs.Recommended applications/ industries: The results of this study indicated the antibacterial effect of the Polylophium involucratum essential oil on some pathogenic bacteria, especially Streptococcus mutans and Streptococcus Sanguis, which can be used as a herbal antibiotic with fewer complications than usual antibiotics for treatment of disease. Manuscript profile