The current mining method, sublevel caving at the Kiirunavaara iron ore mine, has induced large scale subsidence to the hangingwall. The orebody dips, on average, 60° eastward. Therefore the subsidence is developing toward the city of Kiruna, the railway and other infrastructure. One of the most important factors which can affect the hangingwall subsidence is the existence of large-scale geological structures in the hangingwall. The 2D distinct element code UDEC was used in this work to evaluate the effect of geological structures on the hangingwall subsidence. One so called "basic model" was run without any geological structures. One structure set with the dip in the interval 50° - 90° to the east has been then analyzed. The failure surface at each mining level was defined for the different models through failure indicators e.g. yielded elements in shear and tension and surface critical vertical displacement. To evaluate the effect of each orientation on the hangingwall subsidence, the break angle was calculated at each mining level. The results showed that inclined structures had an obvious effect on the extension of the failure surface on the hangingwall. All models with large-scale structures showed a decrease of the break angle compared to the basic model. The structure orientations showed a tendency to govern the direction of shear and tensile failure in the models. The results indicate that it is important to identify the dominating structures and their orientation and the structural geological domains. Keywords: Numerical analysis, Geological structures, failure surface, Break angle.