Background: Masticatory muscle pain is associated with autonomic disorders of different intensity; their identification leads to a more accurate diagnosis and a differentiated treatment. Currently, various scales and autonomic tests are used for this purpose, as well there are being developed neurophysiological diagnostic methods. For this purpose, electrodermal activity is being studied since the 1950s, which currently is further advancing due to modern recording and information processing technologies. The aim of the study was objective assessment of sympathetic nervous system activity (tonus, provisioning) in patients with masticatory muscle pain, with the application of the spectral analysis of electrodermal activity. Material and methods: Thirty-four female patients with masticatory muscle pain were enrolled in the study. NeuroMEP (Neurosoft) diagnostic system was used to record electrodermal activity. For the assessment of the autonomic tone (rest) and autonomic provisioning (maxillary clenching test) there were used EDASymp, EDASympn, meanTVSymp, minTVSymp, maxTVSymp sympathetic indices, identified experimentally at the University of Connecticut (USA). Results: The comparative analysis of the indices has shown that EDASympn and meanTVSymp are reproducible and characterize the activity of the sympathetic system during the rest and maxillary clenching. The range of values of sympathetic indices at rest/maxillary clenching were: EDASympn (0.222 – 0.668/0.360 – 0.4872 u.n.) and meanTVSymp (0.883 – 1.015/1.055 – 1.245). Conclusions: EDASympn (normalized sympathetic component of the electrodermal activity) and meanTVSymp (index of sympathetic tone) sympathetic indices allow the objective assessment of the activity of the sympathetic nervous system, being reproducible in patients with myalgias.