End-plate formation in free autologous transplants of previously denervated whole muscles in adult cats were studied with a histochemical technique for cholinesterase. Grafts from 5 to 40 weeks old have been examined. The original end-plates degenerated and could not be seen in transplants older than 9 weeks. New, immature end-plates formet at many sites in the transplants. They were seen as early as 5 weeks after transplantation. They progressively increased in number during the first 12 weeks. In the oldest transplants the end-plates were relatively mature and appeared in clusters or were sacttered.