Many studies have shown that the prevalence of malnutrition in hospitals is high. Our aim in this study is to ensure the systematic use of a preoperative nutritional evaluation (PNE) that ensures simplicity and usefulness in hospital nursing assistance. A total of 96 patients were studied, of whom 31 were diagnosed as having neoplasia and 65 non-neoplasia. For the purpose of this evaluation, the Chang method was used, completed with the application of retarded immunity skin tests. Malnutrition was observed in 71% por patients with neoplasia, mainly corresponding to slight Marasmo grade. In non-neoplasic patients malnutrition was 46%, also corresponding to slight Marasmo grade. In patients with neoplasia, anergy was evident in 54.9% of cases, and accounted for 23.1% in non-neoplasic patients. The development of anergy in both types of patients was significantly greater (p less than 0.05) in patients over 65 years of age. The inclusion of a PNE should form part of the nursing protocols, being used systematically in the study and control of surgical patients.