Abstract It is generally accepted that gingivitis and periodontal disease can be prevented by means of an effective daily plaque control‐ Also in the treatment of periodontitis plaque control seems to be essential.The plaque‐inhibiting capacity of Hibitane is well documented, and the ability of the agent to prevent gingivitis for a relatively short time has been shown. Thus Hibitane is a valuable drug in dentistry in cases when conventional plaque control is difficult or impossible for a limited period of time. The longterm effect of the drug is less known in humans. However, a few studies in selected populations indicate that the effect is preserved after continuous use for several years. Established destructive periodontitis with pocket formation and subgingival plaque seems unaffected by chlorhexidine, but healthy gingival conditions may probably be maintained by two daily applications of the agent. The indications for long‐term use of Hibitane in the mouth are still not satisfactorily clarified. Such use must be regarded and controlled as experiments. Although systemic side effects seem to be rare, some embarrassing local adverse effects have been frequently reported. The staining of teeth and fillings constitutes a serious obstacle to a more generalized use of the agent in dental practice.Several modes of application of Hibitane in the mouth have been suggested. However, the pharmacodynamic properties of chlorhexidine as a plaque‐inhibitor are dependent on a series of complicated chemical reactions and may in several ways be jeopardized by components of a vehicle. Therefore, reliable clinical investigations proving the effect of commercial products containing Hibitane are indispensable before advocating their use.