Aim: To evaluate the amount of apical root resorption of central incisors with periodontal involvement in patients undergoing orthodontic intrusion. Methods: Twenty-eight adult periodontal patients were treated with combined orthodontic-periodontic therapy. After open-flap surgery, the orthodontic treatment started, following the segmented arch technique, and the teeth were intruded. The amount of radicular resorption was evaluated on standardized intraoral radiographs. The influence of intrusion, treatment time, and age and gender of the patients upon apical resorption were also studied. Results: At the end of treatment, mean resorption at the apex was 0.46 mm, 3.46% of the initial root length. No relationship was found between resorption and amount of intrusion or patient gender and age. A poor level of association was reported between resorption and treatment duration. Conclusion: Results suggest that by using light (10 to 15 g) and continuous forces, apical resorption could be kept to a minimum. This also is true in the treatment of maxillary central incisors with marginal bone loss. World J Orthod 2003;4:321–325.