Background: Internet addiction is one of the fast-growing addictive behaviors and is a significant public health problem affecting a large number of people worldwide. Excessive use of the internet among university students increases their risk of internet addiction and related negative consequences. However, there is limited evidence on the status of IA and its consequences among college students in Ethiopia. This study aimed to determine the prevalence and factors associated with internet addiction among medical and health sciences students of College of Medicine and Health Science. Objective; the aim of this study was to assess the prevalence of internet addiction and associated factors among undergraduate students in the college of medicine and health sciences of Bahir Dar University. Method; A cross-sectional study was conducted among Bahir Dar University College of Medicine and Health Science students from August to September 2021. A total of 449 students were selected systematically and interviewed using a structured questionnaire. Bivariate logistic regression was first used and then variables with p-values <.2 were entered to multi variable analysis and finally variables with p-values <.05 used for final analysis. Result; the response rate was 97.3% & the prevalence of internet addiction in this study was 44.1 %( n=198) (95% CI 39.2_48.8). The factors significantly associated with internet addiction were using of smart phones p=0.015 (AOR=8.142, 95% CI; 1.511, 43.8), being permanently online day and night p<.001 (AOR=7.4, 95% CI; 2-3.6), playing mobile games p=.016 (AOR=2.795% CI; 1.2-6.075) and students who had psychological depression p=0.015(AOR=9.726; 95% CI; 1.566-60.4). Conclusion: Internet addiction is growing health problem among students of medicine and health science. The overall prevalence of internet addiction in college of medicine health science, Bahirdar University is in the ranges of global prevalence. The factors with significant association with internet addiction were having smart phones, being online permanently day and night, playing mobile games and psychological depression. In this study the harmful consequences of excessive internet use in this population was due to excessive use of smart phones for games, using the internet permanently day and night and psychological depression