In view of the extensive open pit mining operation at Gaspé Copper Mines Limited, Murdochville, Quebec, a study of an optimum slope design was felt necessary. This paper describes the different steps of the slope stability project: origin and organization to achieve an optimum design. The various phases of the project were: survey of the ore body and topography, investigation of physico-mechanical properties of rocks, structural geological mapping, groundwater study, and detailed study of structural weaknesses. The results were subsequently used to analyse different modes of possible failure of rock mass. The information obtained is being used in redesigning the Copper Mountain pit.