The aim of the study was to determine the antibacterial activity of pure Bacopa monnieri extract on periodontopathogenic bacteria; Porphyromonas gingivalis(Pg), Prevotella intermedia (Pi), Fusobacteria nucleatum (Fn) & Aggregatibacter actinomycetemcomitans (Aa). The minimum inhibitory concentration (MIC), minimum bactericidal concentrations (MBC) and Time kill curve assay were performed to assess the antibacterial effect of both ethanolic and aqueous extract of pure bacopa monnieri against periodontopathogenic bacteria by serial dilution method and colony forming units respectively. MIC values of ethanolic extract were in a range of 25-100 µg/ml for Pi, Fn and Pg and Aa showed a value of 0.8 µg/ml whereas the MIC values of aqueous extracts were in a range of 50-100 µg/ml and that of Aa was 0.4 µg/ml. The time kill curve showed a fast and sharp antibacterial activity of the ethanolic extract over Pi, Fn and Aa at baseline (0 min) whereas Pg showed no growth of colonies at 2 hours.The ethanolic and aqueous extract of Bacopa monnieri exhibited durable antibacterial activity on common periodontogenic bacteria.