A new phenomenon, which increasingly rises among the young generation all over the world, is Internet addiction. Information and communication technology (ICT) has a major influence not only on individual sectors of the national economy (services, industry, agriculture, etc.), but also on free time activities and interests of the young generation. ICT-related free time activities of the young generation have notably changed over the last decade (Slovakia was connected to the Internet in November 1992). The aim of the research was to determine the symptoms of Internet addiction in Slovak secondary school students, i.e. to detect significant differences between the following: a personality trait – addiction, addiction – age, addiction – a place of residence, etc. The standardized questionnaire was used in all regions of Slovakia. We collected data by means of an online questionnaire over the period of more than six months. The research results show that female have more potential to become addicted than male, which could be caused by feelings and sadness (Ha & Hwang., 2014). Some other significant results show that more extroverted students are less Internet-addicted than their less extroverted counterparts. According to Zamani, extroverts prefer social and face-to-face interaction with others (Zamani et al., 2011). Other questions focused on neuroticism - emotional stability, where more neurotic students were more addicted than less neurotic students. Finally, significant results were related to residence. Findings showed that students who come from cities (towns) had higher symptoms of Internet addiction than villagers. Other details of this research are shown in the results and discussion section.