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The use of infrared tympanic thermometers within the medical community (and more generically in the public domain) has recently grown rapidly, displacing more traditional forms of thermometry such as mercury-in-glass. Besides the obvious health concerns over mercury the increase in the use of tympanic thermometers is related to a number of factors such as their speed and relatively noninvasive method of operation. The calibration and testing of such devices is covered by a number of international standards (ASTM, CEN, JIS) which specify the design of calibration blackbodies. However these calibration sources are impractical for day-to-day in-situ validation purposes. In addition several studies have thrown doubt on the accuracy of tympanic thermometers in clinical use. With this in mind the NPL is developing a practical, portable and robust primary reference fixed point source for tympanic thermometer validation. The aim of this simple device is to give the clinician a rapid way of validating the performance of their tympanic thermometer, enabling the detection of malfunctioning thermometers and giving confidence in the measurement to the clinician (and patient ) at point of use. The reference fixed point operates at a temperature of 36.3 degrees C (97.3 degrees F) with a repeatability of approximately +or-20 mK. The fixed-point design has taken into consideration the optical characteristics of tympanic thermometers enabling wide-angled field of view devices to be successfully tested. The overall uncertainty of the device is estimated to be is less than 0.1 degrees C. The paper gives a description of the fixed point, its design and construction as well as the results to date of validation tests.