Halitosis is an unpleasant odour of the exhaled air from the oral cavity. In almost 90% of cases, it is of intraoral aetiology and is, therefore, in the treatment domain of doctors of dental medicine. Due to the lack of awareness and knowledge of the general public and healthcare professionals, patients with halitosis often initially seek therapeutic help from medical doctors. Successful treatment of halitosis is causal, planned and conducted only after an accurate diagnosis. Diagnostic procedures include a conversation with the patient and analysis of clinical data obtained from a detailed medical history, organoleptic and instrumental testing of halitosis, and additional procedures (analysis of tongue coating, salivary tests, examination and treatment of extraoral pathologies). Following the diagnostic procedures, halitosis can be classified as genuine or pseudohalitosis ("imaginary halitosis"). If the patient still insists that their halitosis is present after successful treatment, halitosis can be recategorised as halitophobia. Each of the halitosis category has assigned treatment procedures, prescribed by existing clinical recommendations.