Malnutrition in the elderly is a problem caused by several factors, with increased incidence in hospitals and in geriatric care units. The relation between malnutrition and infections is well documented. The aims of the present study were: 1) an assessment of the validity of six malnutrition screening tools for adults and elderly, having in mind the absence of a gold standard in malnutrition screening, 2) an investigation of the impact of malnutrition in a group of elderly hospitalized patients at risk of hospital acquired infections, 3) an evaluation of the impact of hospitalization and other medical procedures on the nutritional status of the patients and the evaluation of the adequacy and quality of hospital food catering. In the present study, 248 elderly patients were recruited (129 men and 119 women), aged 75,2±8,5 years. Nutritional screening was performed on admission with the use of Nutritional Risk Index (NRI), Geriatric Nutritional Risk Index (GNRI), Subjective Global Assessment (SGA), Mini Nutritional Assessment – Screening Form (MNA-SF), Malnutrition Universal Screening Tool (MUST), Nutritional Risk Score 2002 (NRS2002) and also the combined risk index was calculated. On admission, full clinical and biochemical evaluation was performed, anthropometric measurements and performance status of the patients was recorded. During hospital stay, the occurrence of healthcare associated infections (HAIs) was also recorded. Malnutrition risk varied greatly, ranging from 47,2 to 97,6% depending on the nutrition screening tool used. MUST was the most valid [validity coefficient, (VC) = 0,766, CI 95%: 0,690- 0,841)], while SGA was in better agreement with the combined index (κ= 0,707, p98) were significantly more likely to remain free from HAIs during hospitalization (p=0,003). During hospitalization a significant reduction in body weight (1,7±2,6 kg, png their hospitalization. Therefore, the need for incorporating nutritional screening in clinical practice on admission is emerging. Moreover, monitoring and evaluation during a hospital stay is essential, as well as the creation of nutritional support teams in every hospital and the raise of awareness among health professionals about the importance of 9 sufficient and high quality nutritional elements for the patients, in order to make possible early detection and the treatment of malnutrition with all the means of nutritional intervention that we have