This study examined the relationship between volatile sulfur compounds (VSCs), including hydrogen sulphide (H(2)S), methyl mercaptan (CH(3)SH) and dimethyl sulphide [(CH(3))(2)S], in mouth air of patients and a history of systemic disease. The subjects were 387 residents (174 males and 213 females) of Fukuoka Prefecture, Japan, who participated in an oral and systemic health survey for elderly persons (mean age: 61.8, s.d. 2.8 years). The VSCs were measured using a portable gas chromatograph (OralChroma). The H(2)S concentrations were significantly greater in the 132 subjects with a history of hypertension and the 41 subjects with a history of respiratory disease, including pneumonia, pulmonary emphysema and bronchitis, than in those without such a history. The CH(3)SH concentrations were significantly greater in those with a history of hypertension. The 16 subjects with a history of cerebrovascular disease, including intracerebral haemorrhage, cerebral infarction, and subarachnoid haemorrhage, and the 58 subjects with a history of liver disease, including hepatitis, alcoholic liver disease, drug-induced liver injury, fatty liver and liver cirrhosis, showed significantly greater (CH(3))(2)S concentrations (p < 0.05). These results suggest an association between the production of VSCs in mouth air and systemic diseases such as hypertension as well as respiratory, cerebrovascular and liver diseases.