Halitosis refers to the condition of offensive mouth odour. More than 90% of cases of halitosis originate from the oral cavity. The implicated bacteria (Fusobacterium nucleatum, Prevotella intermedia, and Tannerella forsythensis) are located in stagnant areas in the oral cavity, such as the dorsal surface of tongue, periodontal pockets, and interproximal areas. These bacteria proteolyse the amino acids releasing volatile sulphur compounds. The management of halitosis involves determining and eliminating the causes, which includes identifying any contributory factors, because certain medical conditions are also associated with characteristic smells. Professional advice should be given on oral hygiene and diet, and treatments should include dental scaling, and root planing of the associated periodontal pockets to reduce the bacterial loading. In addition to the normal oral hygiene practice, tongue cleaning and use of mouthwash are advocated. This paper discusses the common aetiological factors, classification of oral halitosis, and its treatment.