Background: Astonishing growth in the internet’s popularity with improvements in its availability and affordability has led to internet overuse and addiction. School students who have social, peer or behavioural problems are more susceptible to internet addiction. Objectives: To determine the prevalence of internet addiction in the school-going adolescents of Aligarh and to measure the association of internet addiction with the socio-demographics of the study participants. Material & Methods: This cross-sectional study was conducted in the schools of Aligarh. 1020 participants were selected through a multi-stage sampling technique proportional to the number of students in each class. Data Collection was done using a questionnaire that included Young’s 20-item Internet Addiction Test (IAT). Results: About 35.6% of the students had internet addiction. Males (40.6%) were significantly (p=0.001) more addicted to the internet than females (30.6%). On bivariate analysis, a higher age group (17-19 years) (OR= 2.152, 95% CI- 1.267- 3.655), male gender (OR= 3.510, 95% CI- 2.187 - 5.634) and internet access at home (OR= 2.663, 95% CI- 1.496 - 4.740) were found to have a significantly higher odds’ for internet addiction. Conclusions: Internet addiction is widely prevalent among school going adolescents and needs attention. © 2017 Elsevier B.V., All rights reserved.