The paper describes the problems, the methodology and the findings related to the documenting of the hidden grave sites from the Second World War and the first post-war years on the territory of the Republic of Slovenia. This was carried out between April 2002 and February 2003 and from August 2003 till May 2004 when the first phase of the national project of documenting all the grave sites from the mentioned period was carried out. The wartime and the post-war grave sites of the opponents of the partisan movement remained undisclosed for more than fifty years. A total of 290 grave sites were documented, 35 of which were located in Karst pits, 7 in mine shafts and shelters, 12 in anti-tank trenches and 236 in burial pits.