The aim of the present study was to assess the prevalence of radiographic alveolar bone loss, as related to selected background variables in 2767 14-year old schoolchildren. Bone loss was recorded when the distance from the cemento-enamel junction to the alveolar crest exceeded 2 mm. The radiographs were magnified approximately 10 times. 3% of the subjects and 18.5% of the sites were excluded because of indistinct radiographic reference points. Radiographic bone loss was found in 4.5% of the subjects. Horizontal lesions were more prevalent than vertical defects. Most subjects with bone loss had 1 (75%) or 2 (22%) lesions. No subject was diagnosed with juvenile periodontitis kind of lesion. The prevalence of bone loss depended on the variables sex, orthodontic treatment and ethnic background.