The purpose of this study was to determine the prevalence of ideal occlusion and other groups of malocclusions according to the Angle classification in 12-13 years old students in secondary school of Zahedan (2007).The samples were 630 students who selected by muli stage random sampling method (315 females,315 males).All samples had permanent dentition,no history of orthodontic treatment ,truma or surgery that could affected occlusion and no syndromic diseas.The samples were examined in natural light by disposable mirror and plastic ruler in centric occlusion.The data were recorded in a questionear for each sample.The data analysed through the chi-square test with level of signification of 5%.The result showed that the prevalence of ideal occlusion and dental malocclusion were ;ideal occlusion 7.9% , CL.I malocclusion 76.9%, CL.II DIV.1 12.7%,CL.II DIV.2 1.4%,CL.III 1.1%.The results indicated that CL.I maloccusion as the most prevalence malocclusion observed in the studied population and the lest prevalence was pertained to CL.III.