The range of the temperature at the skin surface overlying the temporomandibular joint (TMJ) and the origin of the superficial belly of the masseter muscle was investigated in 35 individuals with normal TM joints and 29 individuals with normal masseter muscles. The temperature was measured by a thermistor in contact with the skin. The temperature over the TMJ varied between 32.1 degrees C and 35.5 degrees C (average 34.3 degrees C). The difference in temperature between right and left sides was to an average 0.3 degrees C. The temperature over the masseter muscle ranged from 30.9 degrees C to 35.7 degrees C (average 33.2 degrees C). The difference in temperature between right and left sides was an average 0.4 degrees C. It was concluded that there is a fairly wide range of skin temperature over the normal TMJ and origin of the masseter muscle under the experimental conditions prevailing in this study but that the differences between right and left sides are fairly small. It therefore seems possible to use this thermometric method to assess inflammatory processes and/or changed metabolic activity in the TMJ and masticatory muscles.