Acetic acid was evaluated for its effectiveness to be used as an intracanal medicament. Four studies were conducted to confirm the usefulness of acetic acid in medicating the root canals. Study 1: Bacteriology Acetic acid (in different concentrations) and other intracanal medicaments were examined bacteriologically. The weakest concentration of acetic acid that induced a good antimicrobial action was found to be 2 % when it was in direct contact with the microorganisms. The vapor’s antimicrobial action of acetic acid was clear in concentrations from 30 % and above. Tricresol formalin, and formocresol exerted an antimicrobial activity that inhibited all the microorganisms on the culture media. CMCP induced a milder antimicrobial action while calcium hydroxide showed a low antimicrobial action only in direct contact. Study 2: Histopathology Twenty albino rabbits were used in this study. Different intracanal medicaments were inoculated in the tibia of the rabbits and the tissue reaction was examined histopathologically after different time intervals. Two percent of acetic acid showed a mild reaction that subsided after 14 days.