The study investigated the aetiological factors and management of patients who have xerostomia. The subjects were 100 consecutive patients referred to the Oral Medicine Unit for investigation of oral dryness. A detailed case history was recorded and patients underwent a systematic examination together with sialometry, haematological, biochemical and immunological investigations. Suspected cases of Sjögren's syndrome (SS) were referred for assessment by a rheumatologist and ophthalmologist. Objective evidence of salivary gland hypofunction was found in 39 patients. A definite diagnosis of primary and secondary SS was made in 24 and 15 patients respectively, a further five cases had possible primary SS. Other causes of xerostomia were: undiagnosed diabetes (3); drug-induced (11); therapeutic radiation (3); alcohol-related (3); psychogenic (15) and idiopathic (21). Patients complaining of a dry mouth should be questioned about non-oral symptoms. In total, 40% of patients attending the dry mouth clinic had a diagnosis of SS.