Background: Internet is being used extensively throughout the world as it serves as multipurpose tool for education, research,information,entertainment, social networking etc. The excessive undisciplined use by individuals has led to the emergence of the concept of Internet addiction which may have negative effects on sleep quality. Sleep quality affects the academic performance and interpersonal relationship of students and predisposes them to mental illness. Objectives: To assess the prevalence of Internet addiction and its relationship to sleep quality among medical students of Saveetha Medical College and Hospital. Materials and Method: A cross-sectional study was carried out among undergraduate students of Saveetha Medical College and Hospital using 20-item Young’s Internet Addiction Scale and Pittsburgh Sleep Quality Index (PQSI). 300 subjects were studied by simple random sampling. Chi Square test was used to test the significance (P<0.05). Results: Total prevalence of Internet addiction was calculated to be 24.7% with moderate and severe addiction being 22.3% and 2.4% respectively. From this study, it has been found that individuals with Internet addiction have 20.3% risk of poor sleep quality. P value is statistically significant. Conclusion: The significant relationship was found between internet addiction and poor sleep quality that could affect academic performance, so preventive measures should be taken to promote appropriate internet use among medical students.