ABSTRACT: Aim: Purpose of the study was to judge the prevalence of malocclusion and associated predisposing deleterious oral habits in South Indian teen population. Methodology: Prevalence of malocclusion and treatment need was assessed using the Dental Aesthetic Index (DAI) among a sample of 1000, 12 and 15-year-old school children in prominent South Indian cities, who received no treatment before or during the study. Subjects were also assessed for deleterious oral habits. For statistical analysis, Chi-square test was wont to test the correlation of habits with mean DAI score and malocclusion traits. Results: Mean DAI score was 26.81±5.25. Nearly 52% of the study sample presented with malocclusion, starting from ‘definite’ to ‘handicapping’ supported the DAI scores. The prevalence of varied deleterious oral habits was 21.2%. About 35% of youngsters with any oral habit developed malocclusion as compared to those with none habit (P value=0.014). Tongue thrusting, mouth breathing and thumb sucking habits had a major impact on malocclusion.Conclusion: It was evident from the results of our study that presence of malocclusion directly depends upon the presence of deleterious oral habits in general.