The purpose of this study was to investigate the long-term outcome of treatment with reverse headgear in young individuals with a reverse overjet and a skeletal Class III malocclusion due to maxillary deficiency. Lateral cephalograms were obtained from 21 subjects (8.4 +/- 1.5 years; 17 girls and four boys) of an original sample of 30 consecutively treated young patients who were followed for 8 years after active treatment. There was a drop-out of nine subjects; their dentofacial morphology at start of treatment did not differ from those who remained in the study. The remaining subjects were divided into a stable group and a relapse group. The results revealed that two out of three patients maintained a positive overjet 8 years after active treatment. The immediate treatment outcome in the sagittal plane was the same for the stable and relapse groups, but lower face height increased (P < 0.08) and the mandibular plane angle opened (P < 0.05) more in the relapse group. During the 8-year follow-up period, the dental compensation was similar in both groups, but the mandible outgrew the maxilla by four times in the relapse group, compared with twice that in the stable group. In young individuals diagnosed with maxillary deficiency treated with reverse headgear and who have an immediate positive treatment response, there is a potential risk that about one-third might be candidates for orthognathic surgery later in life, because of an unfavourable growth pattern.