It is known that almost one-third of patients who seeks treatment for bad breath do not have genuine halitosis. Halitosis can occur even in cases when the malodor is not perceived by those around the patient and can neither be confirmed by organoleptic tests, nor by sulfur portable monitor readings. In such cases, these patients have been considered as halitophobic or have pseudo-halitosis. The complaint might signal the existence of a chemosensory dysfunction. Factors associated with taste and smell perception can be potentially connected to the occurrence of oral malodor. The threshold values of volatile sulfur compounds that have been used to establish the diagnosis of genuine halitosis do not take into account that the patient may perceive low levels of these and of other volatile compounds through retronasal olfaction. The current concept of halitosis requires the presence of a signal that has been based on equipment results, from the olfactory perception of the examiners and of those who interact with the patient. Nevertheless, the concept does not encompass the symptoms of halitosis. This paper addresses some of the possible causes of chemosensory dysfunction and proposes a new definition for halitosis.