Background: One of the public health concerns today is the increasing use of the internet especially among adolescents and the appearance of internet addiction problems. Although using the internet to students represents great benefits, it has despised consequences on their mental health such as depression, anxiety, and stress. Objectives: To estimate the prevalence of internet addiction among Zagazig University students and to identify its association with mental health using DASS-21 scales. Methodology: Across sectional study was done on 246 randomly selected students at Zagazig University during 1^st term of the academic year 2023/2024 representing both males and females using a cluster sampling technique. A self-administered questionnaire was used. It consisted of three components: the first component comprised sociodemographic data, which included age, gender, and collage, the second part represented a young scale for the detection of internet addiction, and the third part was an Arabic version of Depression Anxiety Stress Scale-21 (DASS -21) to evaluate mental health of studied participants. Results: Prevalence of internet addiction was 73.2% among the studied group. There were statistically significant associations between internet addiction, gender, degree of academic achievement, place of living, students-parents relationship, income, depression, anxiety, and stress. Also, they were the predictors of internet addiction with odds ratios (14.16, 27.72, 24.55, 24.61, 3.32, 1.94, 2.51, 2.55) respectively. Conclusion: Prevalence of internet addiction was 73.2% among students. Female, bad degree of academic achievement, living away from family, bad students-parents relationship, enough or more family income, depression, anxiety and stress were predictors of internet addiction.