Compression members, such as columns or walls, mainly have to carry vertical loads. In addition, they experience bending moments due to the rotation of adjacent components, such as slabs or beams. If rotations occur about two axes or the compression member is, in addition to a uniaxial bending moment about the weak axis, part of the bracing system and therefore loaded with horizontal forces in direction of the strong axis, bending moments about two axes arise. Although unreinforced compression members made of concrete and masonry can resist considerable bending moments, an adequate calculation method for the determination of the load-carrying capacity in case of biaxial bending does not exist. In order to use the existing load-carrying capabilities of unreinforced concrete and masonry compression members with a rectangular cross-section, a non-linear calculation model is developed for the realistic derivation of the load-carrying capacity and transferred into a design method for practical application. The model is based on systematic analyses of the load carrying capacity of the cross-section, the curvature and the load-carrying capacity of the system. Herein, different material behaviours are taken into account as well as the effects of second order theory for slender compression members.