Anterior temporal area and non-specific facial muscle activity were recorded from 11 patients with unilateral anterior temporal area muscle pain and from 11 matched asymptomatic individuals at various mandibular openings. No significant differences were observed (1) in temporal area EMG activity between pain and non-pain sides and (2) between temporal area and non-specific facial muscle EMG activity between patient and non-patient groups. In relation to increased vertical mandibular opening from centric occlusion: (a) anterior temporal area EMG activity decreased to a minimum level (with further opening, anterior temporal area EMG did not significantly change); and (b) non-specific facial muscle EMG activity decreased to a minimum level (with further opening, non-specific facial muscle EMG increased).