The Žumberak uskoks were a group of settlers on Žumberak who came in migration waves mostly from the areas that were occupied by the Ottomans in the 16th century, and a small part in area of Senj in early 17th century. They are a specific ethno-religious group that their particular cultural pattern distinguished Croatian national body and has long been in dispute question of their origin and nationality. A special feature of Žumberak citizens is a large part of its population belongs to Greek Catholic Church, which has its strongest base over the centuries had exactly the Žumberak area. Uskoks settlers on Žumberak proved to be good warriors and they are used for defense of Croatian land from Ottomans which was the original main target of their settlement, of the deserted area of Žumberak. From immigration in the first half of the 16th century the Žumberak uskoks were involved in the military structure of the Military Frontier, originally organized in Žumberak captaincy, and later in the two companies Slunj Regiment of Karlovac Generalate. Although this graduate thesis focuses largely origins and religious affiliation Žumberak uskoks, his most important part deals with uskoci as soldiers. The two main problematic issues of this work are: who are Žumberak uskoks in as a separate ethno-religious group and who were uskoks as a soldiers and what was their contribution in defending the Croatian land from the Ottomans, and the importance of žumbrak uskoks in the system of the Military Frontier.