Although many epidemiological studies defining child sexual abuse prevalence rates in many countries of the world are now available, Italy presents a lack of data regarding this specific issue. Only recently some attempts to define the epidemiology of this public health problem have been tried. Between 2003 and 2010, the Department of Public Health at University of Milan was in charge of one of the more important study of this kind in Italy, involving almost 3000 students aged 18 attending secondary schools in the City of Milan who filled out an anonymous questionnaire aiming at detecting their previous experiences of sexual victimization during childhood and adolescence. After this first edition, the study was replicated among students attending secondary schools in the city of Varese, in the area of Piedmont and in Basilicata (area of Lauria), using the same investigational model and questionnaire. This paper presents the main data collected through four different epidemiological studies using the same methodology and survey tool. Considering at least one of the five different forms of child sexual abuse surveyed (being exposed to pornography, being touched on private parts, being forced to masturbate an older person, being forced to perform oral sex, or being penetrated), the prevalence rate among our samples ranges between a minimum of 12.5% (Varese) and a maximum of 34.1% (Lauria). In Lauria the research reveals a higher prevalence rate of child sexual abuse, especially among the male population, for all typologies of abuse but being touched in their private parts. In all other geographical areas and for all typologies of abuse, there is always a higher prevalence among girls, with the only exception of abuse such as being exposed to pornographic materials.