Introduction: the objective was to assess the severity of malocclusion and orthodontic treatment needs in adolescents from Pasto, Colombia adolescents by using the Dental Aesthetic Index (DAI). Methods: a total of 387 adolescents were randomly selected from a population of 20175 students between 13 and 16 years of age. This cross-sectional study was carried out at Champagnat, San Francisco de Asis and San Juan Bosco high schools. Students wearing orthodontic appliances or reporting a history of orthodontic treatment were excluded from the study. Clinical examination was conducted with the DAI. Mann-Whitney and Kruskall-Wallis analyses were used to compare the DAI scores according to gender and socioeconomic status (SES), respectively. Results: the DAI mean was 34.37 ± 14.71. The 52.7% had between a severe and very severe malocclusion which implies an orthodontic treatment need. Statistically significant differences were found between the DAI scores according to SES (p < 0.001). Conclusions: half of the evaluated adolescents would need orthodontic treatment. In this study, SES was an important variable that is related to the Dental Aesthetic Index scores.