Bad breath is a major concern to the general population and a source of an important profit industry world wide. Between 50 and 60 per cent of the population suffer from chronic halitosis. This can have consequences for private or professional life. Reasons can imply many specialities: ENT, gastro-enterology, pneumology, hepatology, genetics and psychiatry (a high percentage of the patients who come to the clinic with a primary complaint of halitosis do not have a detectable problem). Nevertheless, 85% are stomatological and are explained by the release of volatile sulfur compounds. These substances have a very offensive odor in very low concentrations. A specialized device called a halimeter is available to measure the volatile sulphur compounds in mouth air but in practice the objective assessment of malodor is still best performed by the organoleptic method. A careful examination can determine the patient's problem in most cases. Initial treatment strategy should focus on the exact cause and on oral hygiene. In addition to the usual recommendations, the daily use of tongue cleaners is very beneficial. Other than etiologic therapy, masking can be achieved by oral care products (mouth rinses, toothpastes, chewing gums) which contain metal ions, especially zinc, that inhibit odor formation because of its affinity to sulphur compounds.