Aim: The aims of this study were to examine and compare the prevalence od Internet addiction among students of second year undergraduate and integrated studies, first year graduate studies and fourth year integrated studies at Josip Juraj Strossmayer University in Osijek, and association between Internet addiction and sex, socioeconomic status, academic success and personality traits. Design: Cross-sectional study Participants and Methods: The study included students of second year undergraduate and integrated studies, first year graduate studies and fourth year integrated studies at the Josip Juraj Strossmayer University in Osijek. The research was conducted via an anonymous selfadministered questionnaire that consisted of questions pertaining to socio-demographic characteristics, Kimberly Young questionnaire about Internet addiction and Questionnaire about personality traits. Results: The analyzed data were obtained from 730 students at the University in Osijek. The results show that students use Internet mostly for social networks and entertainment. Internet addiction is more common among male students, and socioeconomic parameters, academic success and personality traits were not associated with Internet addiction among students. Conclusion: Internet addiction represents an important public health problem and challenge in Republic of Croatia with even prevalence among students on various levels of study.