The effect of damage to the follicle and of superficial positioning of tooth germs after replantation or autotransplantation was studied in green Vervet monkeys. Radiographs were taken immediately after surgery and 3, 6 and 9 months postoperatively, whereafter the animals were sacrificed. The tissue blocks were sectioned in step serial sections along a frontal plane and histologic and radiographic evaluation was made. Tooth germs whose follicle was either damaged or removed showed no sign of eruption, while tooth germs which were replanted with an intact follicle were fully erupted within 3 months. Non-operated control teeth were fully erupted within 6 months. Histologic examination revealed that roots of replanted teeth were only slightly shorter than the non-operated control teeth. Transplantation of tooth germs in different positions in relation to the alveolar crest showed that teeth placed in their original position attained an average tooth length of 12.5 mm, whereas teeth placed in a semi-erupted position achieved an average length of only 9.7 mm. A control group of non-operated incisors demonstrated an average tooth length of 13.7 mm. This study indicates that damage to the follicle at the time of replantation of tooth germs is of major importance for tooth eruption and that placing tooth germs in a semi-erupted position adversely influences later root development.