Halitosis is a frequent complaint which is estimated to be found in around 50 to 60% of the general population and that carries serious personal and social repercussions. Although the majority of cases are due to oral problems, it is considered that 10-13% of halitosis cases are of extraoral etiology. In these cases the responsibility of the general dental practitioner, who is frequently the first person to examine and treat these patients, is to refer the patient for evaluation to an otorhinolaryngologist in order to rule out the presence of chronic tonsillitis or chronic sinusitis. If the otorhinolaryngologist does not detect alterations concerning his specialty, the digestive system should be explored in order to detect gastric pathology, obstructions or inflammatory gastrointestinal processes, the liver to rule out hepatic insufficiency or cirrhosis, the endocrine system to exclude diagnoses of diabetes or trimethylaminuria, the airways to rule out bronchiectasis or pulmonary abscesses, and the kidney to eliminate possible renal insufficiency. Finally, in the absence of any systemic organic pathology, the possibility of halitosis of psychiatric etiology, which requires the patient's psychological profile to be checked by the corresponding specialist, should be considered.