OBJECTIVE To assess the orthodontic treatment need of 12-year-old Brazilian school children using the Index of Orthodontic Treatment Need (IOTN). METHODS One experienced examiner evaluated the IOTN's dental health component (DHC) and its esthetic component (EC) in 1,182 individuals from 50 randomly selected state schools of Rio de Janeiro. He also requested that these students score their own EC (self-perception). RESULTS The DHC showed that 51.1% of the children had no/little need, while 26.7% had a need/high need/priority for orthodontic treatment. There was no significant difference between the two sexes (P=.156). According to the EC, esthetics were good in 59.1% of the children, borderline in 32.7%, and unattractive in 8.1%. The self-perception of the EC showed that 89.0% judged themselves as having good esthetics, with girls significantly more critical than boys (P=.035). The statistical correlation between EC (examiner) and EC (children) was low (kappa coefficient=.13). CONCLUSIONS About half of the scored Brazilian 12-year-old schoolchildren had no/little need for treatment. Orthodontists were more critical in their esthetic evaluation than the children themselves, with girls being more critical in self-perception than boys.