Internet addiction has become a harmful behavioral problem found to be highly prevalent in high school and college students. Many studies demonstrated significantly association between Internet addiction and depression.

To study the prevalence of Internet addiction and the association between internet addiction and depression in medical students, faculty of medicine, Ramathibodi hospital.

A cross-sectional study was conducted. Participants were the first to fifth-year medical students who agreed to participate in this study. Demographic characteristics were derived from self-rated questionnaire and were analyzed by descriptive statistics. Thai version of Young's Internet Addiction Diagnostic Questionnaire and Thai version of Patient Health Questionnaire (PHQ-9) were used to assess internet addiction and depression, then Chi² test and logistic regression were used to analyze the associations between internet addiction, depression and associated factors.

From 705 participants, 24.5% had internet addiction and 29.0% had depression. There was statistically significant association between Internet addiction and depression (odd ratio: 1.92; 95% confidence interval [CI]: 1.34–2.77, P-value<0.000). Logistic regression analysis illustrated that the Internet addiction group had risk of depression 1.58 times higher than the group without Internet addiction (95% CI: 1.04-2.38; P-value<0.031). Academic problem was found to be a significant predictor of both Internet addiction and depression. Furthermore, Internet addiction, relationship problems with friend and lover, and health problem were also significant predictors of depression.

Internet addiction was common psychiatric problem which associated with depression among medical students. We suggest that surveillance of Internet addiction should be considered in medical schools.