The diploma thesis deals with the theme of negative effects (forms of risk behaviour) at elementary schools pupils in Český Krumlov and mentions valid legilslation in the field of the risk behaviour primary prevention at school-compulsory choldren and youngsters. The theoretical part describes chosen socially-pathologic effects, the system of primary prevention and MŠMT legislation and other ministries as well in the field of risk behaviour prevention, as well as preventive aktivity of the institutions and organizations in the area of the city of Český Krumlov according to valid laws. The diploma thesis in the practical part includes empirical research performed at chosen elementary schools in Český Krumlov among teachers mapping their experience with the most frequent risk behaviour forms of pupils and further their knowledge and valid legislation usage inthe field of preventation both at schools and duringafter-school activities.