Periodontal condition, plaque situation, and gingival status were studied longitudinally on five different occasions before, during, and after a full period of routine edgewise treatment in thirty-eight adolescents, 11 to 12 years old at the start. Extraction of permanent teeth was part of therapy in all cases. Thirty-nine matching persons who had not had any orthodontic treatment served as a reference group and were examined in an identical way. Loss of attachment was recorded with a periodontal probe on the mesial, distal, and facial surfaces of all permanent maxillary teeth except the second molars. A particular oral hygiene program was followed carefully by all orthodontic patients. The response of the preventive program was reflected in good or excellent oral hygiene and gingival condition throughout treatment. While no differences were registered during active therapy, after removal of the fixed appliances the orthodontic patients had significantly lower plaque scores and less gingivitis than the untreated persons. With regard to loss of attachment, there were no statistically significant differences between the two categories of patients at any of the five examinations. In fact, periodontal condition was excellent in both groups and the average loss of attachment was less than 0.1 mm. per surface. Although it was not possible with the methods used to demonstrate any statistically significant difference in periodontal condition between the treated and untreated adolescents shortly after band removal, the need for extended long-term studies is evident, as discussed. Such follow-ups are planned for both categories of patients in this study.