The topic of this paper is the state border and the protection of the state border. Through a short introduction and elaboration of the topic, we will see all the peculiarities related to the state, from its determination to the type of borders and the way of marking. In the continuation of the work, the state bodies that control the state border, what is their role and importance in maintaining order at the borders will be discussed. The topic related to the state border of the Republic of Croatia, its land and sea borders was further discussed. The following is a part of the paper that deals with the partrelated to unresolved border issues of the Republic of Croatia and its neighboring countries. One ofthen avoid able items will be the topic of the law on the control of the state border, as well as Frontex as themain European agency for the protection of state borders of the European Union, and the Schengen European area. At the very end, the topic related to the protection of the state border at sea was discussed, with the attachment of the minutes on the actions of police officers when catching a foreign vessel in violation of the law on state border control.