Dept of Anatomy, Rajah Muthiah Medical College, Annamalai University, Annamalainagar, India The central representation of the muscles of mastication within the trigeminal motor nucleus in the Bonnet monkey has been investigated using HRP tracer technique. The representations of jaw-closers within the dorsolateral main mass of trigeminal motor nucleus and those of jaw-openers within the ventromedial sub-group are similar to the earlier findings. In addition, the somatotopy of the muscles exhibited within the nucleus correlates well with their topographic relationships. Moreover, the dual representation of lateral pterygoid, observed in the main mass and in the ventromedial subgroup, a feature hitherto not reported, could probably be justified by the dual role of this muscle in closing and opening the jaw.