Within the project of the Priority Programme (SPP) 1542 "Concrete light", which is funded by the German Research Foundation (DFG), unreinforced UHPC columns with square and rectangular cross-section were tested under axial compression in the subproject "Cross sectional adaption for rod-shaped elements in compression". The results were compared with test series of other researchers. The focus of the study was on the buckling behavior of columns with different conditions of end support. A hinged and a fixed support have been applied for these experiments. In addition to an analysis of the failure process, the results were compared with the Euler buckling load and the normal stress in consideration of second-order effects. Concluding, advantages and disadvantages of both approaches are presented, compared, and discussed.