The diffusion of information and communication technologies among children, youth and adults has become an evolving phenomenon. The end of the last century was characterized by rapid technological development and by deep changes in several aspects of human activities, often described as orientation of the world to the “knowledge age“. Such changes have led to many discussions about the roles of upbringing and education as well as ICT in lessons and learning in a new era and, of course, also about the negative effects of ICT mainly on children and the youth. We focused our attention on the effect of ICT on contemporary adolescents, both in terms of its use and possible misuse, particularly in the field of possible ICT addiction. We gave the questionnaire of our own construction to a group of adolescents: there were 1542 student respondents at the age from 15 up to 23, with an average age M=16.99, Sd=4.28, 647 boys and 895 girls. The independent variables were: gender, respondents’ age, the type of attended school, i.e., secondary vocational school=106 respondents, college=697 respondents, grammar school=739 respondents, evaluation marks from the last school certificate of the Czech language and Math. The obtained data were subjected to factor analysis. Programme Varimax orthogonal (NCSS) was used and according to Cronbach’s alpha (0.86), a critical value |0.30| was selected. 3 factors were generated: F1 Tendency to ICT addiction, F2 ICTa study aid and F3 Current daily use and misuse. More than a half of the respondents use daily this combination of ICT equipment: a PC, a laptop, a tablet and a mobile phone. We found out that the level of addiction to the internet is average; the internet as a study aid is used exceptionally frequently, daily use and misuse is slightly below average. Jan Lašek, Petra Kalibová, Jana Andršová Czech republic 73Adolescents and Information and Communication Technologies We chose the internet as a representative of all possibilities of ICT, as an easily accessible medium of contemporaneity. Based on a factor analysis, it can be stated that the more the internet is used for studying, the more possible the addiction to it is and also the tendency to its daily use and misuse.