The muscle fiber fascicles of the temporo-masseter complex of the cat were minutely dissected. Some heads were embedded in paraffin while others were put into methyl-methacrylate resin and sections were made. The results of this anatomical study demonstrate that this complex consists of the masseter muscle, the temporal muscle and two well individualized transitional fascicles: the maxillomandibularis and zygomato-comandibularis muscles. The masseter and temporal muscles are composed of individualized compartments in which the orientation and aponeuroses of the fibers of which they are composed differ with regard to the centric occlusion plane. The masseter muscle consists of a superficial fascicle made up of two layers, an intermediate fascicle, and a deep fascicle composed of two layers. The temporal muscle consists of one anterior orbital part and one posterior temporal part. This structure is in accordance with the mammalian archetype described by Gaspard and Saban. These findings should lead towards a homology-based nomenclature founded on comparative anatomy studies of mammalian species. Such a classification would permit the comparison of results obtained from physiological and histochemical studies of these complex muscle fibers when they are published by different researchers.