1. Three types of experimental trauma to an epiphysis were carried out in rabbits. 2. A small part of the central portion of the epiphysis can be damaged and result in only mild or moderate growth interference. 3. When the entire peripheral portion of an epiphysis is damaged, marked growth limitation and deformity can be expected. 4. Extensive damage to or destruction of the central area of an epiphysis will result in a most marked interference in growth, but with less deformity. 5. It is noted that an osteocartilaginous exostosis may result when a patch of epiphyseal cartilage cells is displaced outside the shaft of the bone. 6. Extreme care to avoid damage to an epiphysis should be taken when bone surgery is necessary in children.