Background: The elderly patients with fragility show different physiological changes, so they are given polymeric diets to maintain and/or alter their nutritional status. The aim of this paper is to demonstrate the effect of changing a standard polymeric diet and a standard diet on nutritional status in elderly patients with fragility., Methods: Clinical randomized controlled trial in 23 elderly patients, 70 years of age or older, with fragility, hospitalized in a Internal Medicine Unity in a period from July to December 2014. Nutritional status was determined through Minimum Nutritional Consulting (MNA) and body mass index (BMI). Descriptive statistics, Chi square, Student t test and McNemar., Results: In the G1: 12 patients were in the G2 and 11, a positive change was observed in the nutritional status G1 initially being 14.00 (malnutrition) and end 22.75 (risk of malnutrition). According to BMI (kg/m2) was evident at the beginning 25 % of patients (3) with mild malnutrition, but the final results show figures with a zero percentage of malnourished patients., Conclusions: The use of standard polymeric diet increases body weight, BMI and nutritional status in elderly patients with fragility.