In recent years, technology development and increased availability of the internet have led to the emergence of cyberbullying. The aim of this paper was to determine the prevalence of cyberbullying among social work students, and to examine the relationship between certain online activities and the internet addiction with cyberbullying. 126 social work students in Zagreb participated in this study. Online survey was used for data collection. The questionnaire consist of Standardized Measuring Instruments: The Internet Addiction Test (Young, 1998.) and European Cyberbullying Intervention Project Questionnnaire (Del Rey i sur., 2015.) and questions about online activities, and sociodemographic characteristics. Results show that 17,45% of college students had been cyberbullied, 22,2% had cyberbulling someone else, and 8,7% of college students are both a perpetrateor and a victim. Thus it was established that being cyberbullyied, and cyberbullied someone else was significantly positively correlated. Furthermore, it was shown that some online activities, such as using social networks, blogging and online shopping were significantly positively correlated with participation in cyberbullying. It has also been found that college students who show moderate and severe levels of internet addiction are more likely to participate in cyberbullying than those who show mild levels or no sign of internet addiction. Concequently, the paper presents recommendations for the prevention of cyberbullying and guidance for future research in this area.