In the background of the great expectations that the international community has had since the end of the Cold War, and in regard to the rivalry between the major world powers (the US and Russia), that have burdened the performance of the United Nations as a global institution striving for global peace and security, this graduate thesis examines two episodes that are generally considered UN's weak points and stains. These are the conflicts in Srebrenica and Rwanda. The introductory part of this thesis provides a narrative presentation of the social, political and international context that led to the crystallization of the genocidal process in Bosnia and Rwanda. The thesis shows that genocide was not necessary a consequence of a particular chain of events or the implementation of a malicious plan. Its cause lies in processes where many internal and external (international) stakeholders have been actively involved. This thesis also shows that genocide is an event that consists of a series of cases of collective violence and mass crimes, and the direct consequences of genocidal policy are most evident in the number of genocide victims. Utilizing the research design of comparative analysis and binary comparison, this thesis sheds light on the UN initiative in Bosnia and Rwanda and concludes that, from an institutional point of view, the UN has failed to stop mass killings, rapes, destruction and desecration of cultural heritage. Indeed, this paper concludes that, during the nineties, the UN in Bosnia and Rwanda was just a bystander to genocide.