The central theme of this paper is the discovered mass graves in the area of the Croatian Danube region, with the aim of the research, classification and analysis of 71 discovered mass graves in the said area. The initial definition is the one that defines mass graves as places where the remains of three or more people were illegally buried, without signs and measures of respect for the remains. Mass graves as a means of ethnic cleansing are one of the clearest indicators of the implementation of ethnic cleansing, taking into account that it is described as a political design that enables the creation of an ethnically pure, homogeneous state. That is, as a planned and deliberate, violent removal of the residents of a certain area who are homogeneous, but undesirable for certain characteristics such as religion, nationality, gender, etc., using force and methods of intimidation to remove persons of another ethnic or religious group from a certain area. In the area of the Croatian Danube region, this political project in the context of mass graves was already reflected in mid-July 1991 and the creation of the first mass graves of the victims of the Homeland War, both in the area of the Croatian Danube region, but also in the entire territory of the Republic of Croatia. This paper analyzed, classified and investigated all discovered mass graves in the area of the Croatian Danube region, where the largest number of mass graves from the Homeland War were found. In this sense, if one takes into account the premise that the areas where the largest number of mass graves were found are those that were exposed to the most severe destruction and suffering, according to the number of mass graves discovered above, it confirms that the area of the Croatian Danube region was the scene of the most severe destruction and suffering. The aforementioned conclusion also stems from the discovery of the first mass grave from the Homeland War, from which the remains of victims, civilians forcibly taken and detained in Tenja at the beginning of July 1991 and killed in the middle of the same month in 1991, were exhumed. At the same time, this conclusion is also confirmed by the discovery of the largest mass graves - the execution site at Grabovo, Ovčara and the largest battlefield clearance grave at the New Cemetery in Vukovar. The analysis of mass graves was carried out using the inductive and historical method in order to achieve the goal of this research. The inductive approach follows the logic of analyzing individual cases on the basis of which a general conclusion is reached. At the same time, the work is followed by the analysis of individual cases, ie mass graves, within which, in such an individual analysis, the use of several scientific methods is interwoven as part of the processing or research of each grave. In this sense, the analysis of each mass grave was subjected to the historical method, the classification method and the counting method. Furthermore, in the context of the analysis of mass graves, a categorization of mass graves was originally designed with new theoretical considerations. Namely, in the previous discourse, the prevailing categorization was that mass graves were divided by the way they were created into mass graves - execution sites and battlefield clearance mass graves. During the investigation of mass graves, it was determined that the previous division was insufficient, and a new categorization was proposed that includes mass graves – gathering sites. In relation to mass graves - execution sites, the analysis determined that the smallest number of mass graves corresponds to this categorization, which is obvious considering that the clearest characteristic of mass graves is their concealment. Precisely for this reason, the largest number of mass graves (64.7%) corresponds to the categorization of gathering places, that is, those graves that were dug further from the place of execution and that represent places that have the above-mentioned characteristics of mass graves. The graves created by the cleanup of the battlefield represent those that correspond to the provisions of international humanitarian law in relation to the almost minimum legal obligations for victims of armed conflicts - burial in maintained and marked grave sites in accordance with the victim's religion and the exchange of information about the victims and their burial locations. The research showed that out of 71 mass graves, 13 of them correspond to those that can be categorized as graves created by the implementation of battlefield clearance. In this sense, it can be quite clearly concluded that the Serbian forces almost completely ignored the provisions of international humanitarian law, as shown by all the presented dimensions of ethnic cleansing.