Transplants of the cranial portion of the dog sartorius muscle were able to generate 70% of control force after 3 months if the artery, vein, and nerve were reanastomosed. Our histological and histochemical findings correlate with the functional findings. In a separate group of animals that had their muscles denervated prior to replantation, no collateral sprouting was noted and no function could be recorded when the nerve was stimulated proximally. These findings suggest that clinical application of free muscle transplantation is strongly supported by this animal model if due consideration is paid to surgical procedure and anatomical structure.