Measuring the prevalence of malocclusion and treatment need in a population is useful for the planning of orthodontic services. In addition, knowledge concerning the attitudes of patients to malocclusion is becoming increasingly important in orthodontics. Without a satisfactory estimate of the need and demand for treatment it is difficult to develop and organize a meaningful service. The aims of this investigation were to estimate the need for orthodontic treatment in 12-13-year-old school children in urban and rural schools in Latvia. Five hundred and four school children aged 12-13 years were examined using the Index of Complexity, Outcome and Need (ICON). The children were invited to complete a questionnaire about treatment need and their appearance. The survey was carried out in four urban and five rural school settings. There were no statistically significant differences in treatment need between rural and urban settings or between boys and girls. However, there was a difference in ICON scores between Riga and Daugavpils, with a greater need for treatment in Daugavpils. Individual responses to questionnaires illustrated a correlation between individuals who expressed dissatisfaction with the arrangement of their teeth and treatment need according to the ICON score. The overall prevalence of individuals needing orthodontic treatment in Latvia was 35.3 per cent, but this figure masked considerable variation between schools. For example, a greater need was found in Daugavpils than in Riga. This difference is not fully explained but could be due to genetics, the individuals in Daugavpils being mainly of Russian origin. The individuals' perception of the arrangement of teeth and the need for treatment correlated significantly with the ICON score.