Malnutrition is one of the most common comorbidities in the elderly. Despite several screening and assessment tools, the diagnosis can be difficult in some cases. In the geriatric population, classical anthropometry does not help very much. For that reason there is a need for further diagnostic criteria. Bioelectrical impedance analysis (BIA) is a fast, low-cost and non-invasive method, which has shown its value in several fields of medicine. Whether this method could be a useful part in the diagnosis of malnutrition in geriatric patients, is the question of this study. In comparison with the Mini-Nutritional Assessment (MNA), serum-albumin and other diagnostic markers of malnutrition, especially the phase angle (50 kHz) of bioelectric impedance analysis showed a consistent correlation with most of the parameters. The calculation of body-fat mass and fat-free mass from bioelectrical impedance analysis is not yet sufficiently validated for geriatric patients. In this study there was no good correlation of the BIA-calculated body-fat mass and fat-free mass with the observed nutritional parameters.