Background:The recent years have seen a major upsurge in Problematic Internet Use. This rise is because of easy access to internet more so among adolescents. Problematic internet use can lead to diverse effects in individuals. Aggression is one of the psychiatric co-morbidity seen in Problematic Internet users. Aims: We aimed to determine the relationship between Problematic internet use and aggression among adolescents. Methods: We conducted a cross-sectional study using convenience sampling. A total of 200 high school and intermediate college students completed the structured questionnaire. The severity of Problematic Internet Use was assessed using Young's Internet Addiction Test (IAT) and aggression was measured using IIPAggression Scale. Results: Among 200 participants, 91(45.5%) were male and 109(54.5%) were female with mean age of 16.37±1.45 years. Mean duration of Internet use was 3.6±1.82 years. 45%, 17% and 2% subjects had mild, moderate and severe dependence respectively based on IAT scores. Pearson correlation showed a signicant positive correlation between Problematic Internet Use and aggression (r: 0.61, p value < 0.001). Chi square revealed statistically signicant association between duration of internet use and aggression scores. Conclusion: Problematic Internet Use is strongly associated with aggression among adolescents. Awareness regarding Problematic Internet Use by educating the adolescents would prevent forthcoming negative consequences.