The pathophysiology of burning mouth syndrome (BMS) is largely unknown. Thus, the aim was to study oral mucosal blood how in BMS-patients using laser Doppler flowmetry (LDF). Thirteen EMS patients (11 female, two male; mean age +/- SD 64.3 +/- 7.9 years, mean disease duration 18.9 +/- 6.2 months) and 13 healthy non-smoking controls matched for age and gender (11 female, two male; mean age 64.7 +/- 8.1 years) were investigated. Using the LDF technique mucosal blood flow (mBF) was measured at the hard palate, the tip of the tongue, on the midline of the oral vestibule, and on the lip. Measurements were made at rest and over 2 min following dry ice application of 10 s duration using a pencil shaped apparatus. In addition, blood pressure (BP), heart rate (HR), peripheral cutaneous blood how, and transcutaneous pCO(2) were continuously recorded. Mucosal blood flow ((mBF) increased at all measurement sites in response to dry ice application (P < 0.001) with peak flow at 0.5-1.5 min after stimulation onset. During the following 1.5-2 min, blood flow decreased at all sires with a tendency to return to baseline towards the end of the observation period. Except for BP and peripheral blood flow, all of the cardiovascular changes exhibited significant changes during the observation period; no differences between groups were detected. When compared to healthy controls BMS patients generally exhibited larger changes in mBF. These changes were significant for recordings made on the hard palate (F[1,24] = 13.9, P < 0.001). Dry ice stimulation appears to be an effective, non-invasive and reasonably tolerable means to investigate mucosal blood flow at different mucosal sites. In general, vasoreactivity in EMS patients was higher than in healthy controls. EMS patients exhibited a higher response on the hard palate compared to controls. These changes in oral blood flow appear to be specifically related to EMS symptoms indicating a disturbed vasoreactivity. (C) 2001 International Association for the Study of Pain. Published by Elsevier Science B.V. All rights reserved.