The results of an experimental electromyographic investigation of temporomandibular arthrokinetic reflex control of the mandibular musculature are reported. Co-ordinated, rapidly adapting and slowly adapting facilitatory and inhibitory reflex changes in motor unit activity in the mandibular musculature were evoked by graduated passive movements of the isolated (but innervated) temporomandibular joint. Induced dysfunction of regionally discrete groups of articular mechanoreceptors was shown to result in specific changes in static and dynamic reflex motor unit activity. The possible clinical significance of these changes is discussed.