In the market many models of performance evaluation exist and softers that they mensuram the performance of the individual, they generate statisticians, they suggest gaps of abilities at last, generates information concerning this individual. With this, the professional in management of people must have conscience that has the necessity of accomplishment of a preliminary work before the choice of the model, the methodology and the instrument of evaluation and not be hostage the modismos taxes for the market. We know that each individual has its idiosyncrasies, that is, possess its proper way to see, to feel and to think the things. Moreover, also they possess its values and personality. That is a complicador factor in the elaboration of a system of performance evaluation, therefore we come across in them with the subjectivity. On the other hand we have the Organizations, we can infer that they (the organizations), also possess its idiosyncrasies, its personality (represented for its culture) and its values. These aspects are important, must be observed in implantation of a system of performance evaluation and points with respect to the necessity to relativize and to analyze the context which we are considering to make an implantation of a system of performance evaluation. In face to the displayed one, I call the attention for two great sources that must be considered and be analyzed more deeply before the implantation of a system of performance evaluation: the subjectivity of the appraiser and the organizacional culture which the appraiser and the evaluated one are inserted. The choice of the model, the methodology and the instrument must be thought of form to look for to minimize the subjectivity of the appraiser and to be in communion with the values, the objectives and the organizacional culture. The deriving results of this type of evaluation must be strategical for the Organization, mapear abilities, add value and retroalimentar the too much systems and/or subsystems of the organization with feedbacks with intention to promote improvements continuous of processes, otimizao of costs and identification of talentos.