The topic of this paper is the history and activities of the Cistercians in medieval Slavonia. Many scholars in European historiography have studied the Cistercians, either through syntheses that include Cistercian history in a broader context or through case studies focusing on specific geographical areas. However, Croatian historiography, apart from some case studies and occasional mentions in syntheses, has not shown a significant interest in the history of the Cistercians. For this reason, the author of this paper decided to analyze the Cistercian activities in the area of medieval Slavonia. The paper specifically deals with the abbeys in Topusko and Zagreb, placing these abbeys within the broader Hungarian context. The author first presents the context from which the Cistercian order emerged, describing the structure and geographical distribution of the order, as well as the daily life of the monks. Historiography has often emphasized the Cistercian pattern of founding abbeys in desolate and remote places. In the context of the Slavonian abbeys, the author discusses how realistic such a perception is. During their activities, the Cistercians came into contact with various social groups. Thus, in paper, the author analyzes the relationships between the Slavonian Cistercians and representatives of royal, noble and ecclesiastical authorities. The paper also discusses the period of commendatory abbots. An important aspect of Cistercian activities was the economy, aimed at achieving self-sufficiency. In this context, the author addresses the fundamental aspects of the Cistercian economy, such as the question of colonization, granges and lay brothers, the conversion of estates into predium, trade, water management, and tax obligations to the General chapter. This thesis also serves as an incentive for future research on the history of the Cistercians in the Croatian historical area.