Chlorhexidine is a very potent cationic chemoprophylactic agent that has a broad-spectrum of activity against gm+ve and gm-ve bacteria. It is both bacteriostatic and bactericidal depending on its concentration. The bactericidal effect, which is achieved at high concentrations, is due to the binding of the cationic to negatively charged bacterial cell walls and extramicrobial complexes. Bacteriostatic effect is achieved at low concentrations which causes an alteration of bacterial cell osmotic equilibrium and leakage of potassium and phosphorus.