BACKGROUND: Patients irradiated in the head and neck region often suffer from severe dry mouth and use acidic saliva stimulating products, which may cause erosion of teeth. PURPOSE: To determine saliva stimulating effects and erosive potential (EP) of acidic saliva stimulating tablets (Xerodent) with and without fluoride in irradiated head and neck cancer patients. MATERIALS AND METHOD: Nineteen irradiated patients (median age 57 years) sucked Xerodent tablets with and without fluoride. Saliva collections were divided into three 10-min sessions in the sequence: unstimulated whole saliva, Xerodent stimulated saliva without fluoride, and with fluoride. Saliva pH was determined without loss of CO(2) and in combination with inorganic measures used to calculate the degree of saturation of hydroxyapatite (HAp) and fluorapatite (FAp). EP was determined directly in all saliva samples by monitored dissolution of HAp crystals. RESULTS: Saliva flow rates increased significantly (15-fold) when sucking both tablets (p<0.001). Major changes in saliva composition caused undersaturation of HAp in some samples. However, no dissolution of HAp occurred in the saliva obtained with any of the two tablets. This was most likely due to the limited drop in pH resulting in saliva that was still supersaturated with respect to FAp. CONCLUSION: Both Xerodent with and without fluoride were evaluated as non-erosive, however, for additional caries protection the fluoride variant is preferable.