Although oral malodor or bad breath is an unpleasant condition experienced by most individuals, it typically results in transient discomfort. At least 50 per cent of the population suffer from chronic oral malodor, however, and approximately half of these individuals experience a severe problem that creates personal discomfort and social embarrassment. The mouth air of chronic malodor sufferers is tainted with compounds such as hydrogen sulphide, methyl mercaptan and organic acids, which produce a stream of foul air that is gravely offensive to the people in their vicinity. Sufferers often make desperate attempts to mask their oral malodor with mints and chewing gum, compulsive brushing, and repeatedly rinsing with commercial mouthwashes. While dental diseases have been strongly associated with this condition, there is considerable evidence that dentally healthy individuals can exhibit significant levels of mouth odor. Proteolytic activity by microorganisms residing on the tongue and teeth results in foul-smelling compounds, and is the most common cause of oral malodor. A specialized device called the halimeter is available to measure the volatile sulphur compounds in mouth air. Many of the manufacturers of bad breath remedies claim that their products contain antibacterial mechanisms with sufficient strength to control oral malodor over long periods of time. None, however, effectively eliminate the problem. Interest in oral malodor research and clinical treatment has increased in the last few years, and this distressing problem is finally getting the attention it deserves.