We have understood Nursing as a collective of various kinds of professional activities involving different educational backgrounds. Within the typical technical division of labour management and assessment concern the nurse. We describe the performance assessment of nurse's aides. Nursing personal participated in the assessment activities from the design of the questionaire to the first draft of data analysis. In the analysis of individual performance assessment we make a distinction betweent "FORMAl" data (refering to racionality) to "NO FORMAL" (related to quality and relationship in the work environment). We also look at the assessment of the service structure. We conclude that this analytical description contributes to the understanding of performance assessment not as a fragment but as a process. This process should have both qualitative and quantitative verifiable goals