As more dentists diagnose and treat the patient with temporomandibular disorders, muscle palpation has been recognized as a valuable diagnostic method. But this method was depended on sensibility and experience of the operator. The purpose of this study was to establish the quantification of muscle palpation by new pressure pain threshold apparatus. Pressure pain threshold (PPT) was determined by the subject when a ramp force applied to the skin changed from "pressure" to "pain". The subjects for the experiments were 90 normal males, 100 normal females and one patient with temporomandibular disorders. Total of 12 sites, anterior temporal M., posterior temporal M., superficial portion of masseter M. and deep portion of masseter M., were measured. The results obtained were as follows: 1. The females showed lower PPT than the males. 2. No difference of PPT between right and left sides was recognized in normal subject, but the significant difference in the patient. 3. PPT of the normal subjects were significantly higher in the posterior temporal M. than the other sites and lower in the superficial portion of masseter M. than the other sites.