Objectives: Describing maloccusion in children aged 12-15 in Chanh Nghia School in Thu Dau Mot city, Sinh Duong province. Method: cross-sectional study. Results: Class I is accounted for 63 percent of the researching population, Class II 14 percent, Class III 23 percent. Ratio of Class I maloccusion in females is 54.0 percent and males 46.0 percent. Ratio of Class II maloccusion in females is 55.8 percent and males 44.2 percent. Ratio of Class I maloccusion in females is 65.7.8 percent and males 34.3 percent. Conclusion: The research reveals the highest ratio of Class I occusion of children in Thu Dau Mot city at 63 percent, Class III malocclusion at 23 percent and Class II malocclusion at the lowe,st 14 percent. Maloccusion in females is higher in males.