This work presents a methodology to develop geological and geomechanic models (3D) and to carry out stability analyses (2D) of rock slopes of open pit mine, based on data of Morro da Mina mine, provided by the mining company VALE. The methodology is divided in two stages: modelling and stability analyses. For the modelling, the software Petrel 2004, which allows the use of geostatistical tools, was used, being possible the spatial distribution of geotechnical information, obtained from borehole cores, for the whole rock mass. The technique of Ordinary Kriging was used. The modeled properties were the following: c`, fi, RQD, Q e RMR. The generated model represented well the spatial distribution of these properties. The stability analyses were carried out using 2D sections and the necessary rock mass parameters were obtained from the geomechanical model. Two types of analyses were carried out: kinematic analyses, with use of the software Dips, from Rocscience, and limit equilibrium analyses of the global slopes and the benches, where the software Slide 5.0, also from Rocscience was used. The Kinematic analyses, carried out considering two sets of joint orientations, suggested that the benches have to receive enough attention in this mine, and the limit equilibrium analyses for circular failure of the benches and global slopes indicated high factors of safety. However, before this work initiating a failure already had happened in one of the sections analyzed. The programs RocData 4.0 and RocProp, both from Rocscience, were used to estimate the Mohr-Coulomb strength parameters, and the programs AutoCAD 2004 and Microsoft Office Excel helped at the development of the input files in the Petrel 2004 and Slide 5.0.