Objective To study the risk factors of alveolar bone loss（ABL）of primary teeth in Chinese children. Methods Caries, restoration, food impact, pulp pathosis, calculus, and periodontal status were examined in 106 children aged 3-10 years old. Bite-wing radiographs of posterior teeth were scanned into computer. The distance from the cemento-enamel junction to alveolar bone crest was measured from the mesial surface of the first primary molar to the distal surface of the second primary molar using Adobe Photoshop 5.0 image analyzing system. ABL was recorded if the distance was more than 2 mm and the lamina dura was absent. All patients were divided into ABL group and non-ABL group. All data were analyzed by SPSS 10.0. Results Alveolar bone loss was found in 31 children（29%）. Most of the affected areas were located at the proximal surface of primary molars. The mean of dmft and proximal dmft in ABL group were higher than those in non-ABL group（P
