A prospective study of 150 consecutive patients with burning mouth syndrome and with a minimum follow up period of 18 months is reported. Factors related to dentures, to vitamin B complex deficiency, and to psychological abnormalities were found to be important, and undiagnosed diabetes mellitus, reduced salivary gland function, haematological deficiencies, candidal infection, parafunctional habits, and allergy might also play a part. Given a protocol for management which takes all these factors into account, some two thirds of patients can be cured or have their symptoms improved.