The aim of this study is to known the prevalence of cyberbullying, and how these students behave. We designed a transversal, descriptive and observational study in two educative centers of Educación Secundaria Obligatoria (ESO) in Toledo (Spain). The sample comprised 190 students of both genders and ages between 11 and 16 years. Results indicated that 46.8% of the adolescents had been bullied by Information and communication technology (ICT). The behaviors and communication channels that are most frequently used to harass, have been offensive messages through mobile and/or Internet and spreading rumors to harm the victim. It is worth noting that almost a third of students harassed not request any help to deal with it. The cyberbullying phenomenon is clearly established in our society and a small percentage of cases it becomes a serious problem.