This thesis is devoted to the stability analysis of a slope in a rock mass characterized by a Block In Matrix structure (BIMsoils). The complex mechanical behaviour of these materials has been widely studied and some characteristics have been found to affect deeply the failure process in unstable slopes: the volumetric block proportion (VBP) of blocks, the block size distribution and the position of the blocks inside the slope. All these characteristics have been analysed in this work, by means of numerical analyses by FEM, implemented in RS2 code, of a simple slope. Four different VBP (25%, 40%, 55% and 70%) were analysed.