The ability of muscle to persist in the brain was explored. Pieces of rat quadriceps muscles were removed, minced and transplanted back into the same animal's cortex. Brains implanted with minced muscle consistently contained substantial grafts for at least 6 months. Histological, immunohistochemical, and electron microscopic examination indicated that the muscle grafts after 6 months contained healthy and well-differentiated myofibers. The long-term survival of muscle cells suggested that this technique will be useful for studies of brain and muscle and for the development of new therapeutic modalities.