Purpose: To evaluate the psychological impact and effect on academic performance of untreated gross dental malocclusion in adolescents. Materials and Methods: A total of 366 (181 girls and 185 boys) adolescents with gross dental malocclusion were selected for the study group. A modified oral aesthetic subjective impact scale questionnaire was applied in face-to-face interviews. Similar data were collected from parents, schoolteachers and one friend of each adolescent selected for the study. Academic performance was evaluated from school records and compared with a control group of 400 adolescents (200 girls and 200 boys) having normal occlusion and an aesthetically pleasing facial appearance. The Kruskal-Wallis H and chi-square tests were used to analyse the data. The correlation between the academic performance of adolescents and the psychological impact of malocclusion was assessed using the Spearman rank correlation. Results: Significant numbers of adolescents (81.1%) were concerned about the appearance of their teeth, with significant gender variation (0.02). 88.5% of the adolescents received comments from others about their appearance. The results differed significantly by gender for 'avoiding smiling' (p = 0.02) and 'participation in social activities' (p = 0.02). The evaluation of academic performance showed that 42.1% of the adolescents with gross dental malocclusion performed below average; this also differed statistically significantly by gender (p = 0.04). Conclusion: Untreated gross dental malocclusion significantly affects the psychosocial well-being of adolescents, who may avoid participating in social activities and tend to underperform in school. Keywords: adolescents, malocclusion, psychological impact