The effect of splinting upon periodontal healing after replantation was studied in 21 green Vervet monkeys (Cercopithecus aethiops). Two maxillary incisors were extracted in each monkey and the teeth were endodontically treated extraorally. One incisor was replanted after 18 min. whereas the other was replanted after 120 min. In 8 monkeys an orthodontic band-acrylic splint was applied for 6 weeks. In 6 monkeys the replanted teeth were splinted for 2 weeks. In 7 monkeys no splinting was carried out. The animals were sacrificed 8 weeks after replantation and the replanted teeth were examined histologically. The following histologic parameters were registered for each tooth: surface resorption, inflammatory resorption, replacement resorption (ankylosis), downgrowth of pocket epithelium and periapical inflammatory changes. All teeth replanted after 120 min. showed extensive ankylosis irrespective of the splinting method. In the 18-minute replantation group, the frequency and extent of replacement resorption was significantly lower in the non-splinted teeth compared to the splinted teeth. No significant changes were found among the other examined histologic parameters. It is concluded that splinting did not improve periodontal healing after replantation of mature teeth in monkeys and apparently exerted a harmful effect upon periodontal healing in teeth replanted after a short extraoral period.