Purpose: Boron is a bioactive trace element found in humans and essential for the growth and maintenance of bone and also has reported anti-inflammatory and antimicrobial activity. Boric acid is a well-characterised boron-containing compound which reportedly can reduce periodontal inflammation. Thus, the aim of the current study was to evaluate the possible bactericidal and/or bacteriostatic effects of boric acid on the periodontal pathogens: Fusobacterium nucleatum and Porphyromonas gingivalis.Materials and Methods: Minimum inhibitory concentration (MIC) of boric acid on F. nucleatum (ATCC 10953) and P. gingivalis (ATCC 33277) were determined by the broth microdilution method. Overnight cultures were diluted to the following starting concentrations: 5x105 cfu/ml for F. nucleatum and 5x106 cfu/ml for P. gingivalis. After incubation for 48h at 37°C in an anaerobic cabinet the absorbance of the cultures was measured. The minimum bactericidal concentration (MBC) was determined by plating an aliquot ofthe cell suspensions on agar plates, and bacteria were counted after incubation at 37°C for 48 h under anaerobic conditions.Results: Boric acid was able to inhibit the growth of F. nucleatum at a concentration of 780 nM and P. gingivalis at a concentration of1.56 μM. The MBC of boric acid was 19 mM for F. nucleatum however using tested concentrations (75 mM-1nm) were insufficient to provide an MBC for P. gingivalis.Conclusion: Boric acid may be a possible candidate for providing local antimicrobial actions on periodontal pathogens and therefore may have potential as a therapeutic intervention in the management of periodontal disease.