The word halitosis derives from Latin, ‘halitus=breath’ and ‘oris disease = mouth condition’ literally meaning bad breath. Halitosis is a symptom, not a disease. It is one of the commonest clinical problems encountered in dental practice. Often the cause is evident in the oral cavity, like an open carious lesion, periodontal abscess or peri-coronal abscess. But if intra-oral causes are not present, systemic contributing factors should be suspected; like lung abscess, acid peptic disease, suppurative pharyngitis etc. In some patients who apparently have good oral hygiene there is a feeling that their mouth stinks and they persistently go from doctor to doctor who tells them that there is nothing wrong and that they don’t have any halitosis. In such cases delusional halitosis should be suspected. The Dental surgeon must assess if the patient needs dental care, medical care or psychological counseling in the chronic case of Halitosis. Sometimes two of the three causes may be culprits. Use of different pastes, mouthwashes or over the counter products can give only temporary relief if proper diagnosis is not made.