Mouth breathing as an oral habit is seldom discussed in detail and as a consequence has tended to be overlooked by dental professionals. Early diagnosis is a key to treatment. A pediatric dentist may be one of the first healthcare professionals to come in contact with a patient who exhibits mouth breathing and thus it is important to have a sound knowledge to perform correct diagnosis and effective treatment. Present review of literature includes etiological factors, clinical features, pathogenesis, diagnosis and management of mouth breathing patients.