PURPOSE: This study reports on the development and evaluation of a telemetry system for recording salivary pH. MATERIALS AND METHODS: The system used an iridium-oxide pH sensor (Metoxy sensor) and was housed inside a mandibular complete denture. It transmitted the data using the AM band (radio frequency of 12.3 MHz) and had a maximum power output of approximately 1 mW with a 3-V lithium battery (capacity 190 mAh). For the clinical evaluation, a 69-year-old woman who was edentulous and had no systemic disease was the subject. RESULTS: Under the conditions of the study, the system was able to operate for 19 hours. The maximum error of transmitted pH data values was pH 0.15 within the range from pH 5.0 to 9.0. The evaluation of the test subject showed that this system operated without problems, and that the pH levels responded appropriately. CONCLUSION: The developed system was shown to successfully record salivary pH, and it functioned as expected in a single test subject.