The Mini Nutritional Assessment (MNA), the Subjective Global Assessment (SGA) and the Nutritional Risk Screening (NRS) are screening and assessment tools aimed at detecting malnourished individuals and those at risk for malnutrition. In our study we tested their applicability in geriatric hospital patients and compared the results of the three tools. We examined prospectively all patients of two acute geriatric wards by the MNA, the SGA and the NRS. 121 patients were included in the study. The MNA could be completed in 66.1% of all patients, the SGA in 99.2% and the NRS in 98.3%. There was a significant association of all three tools with the BMI (p<0.01). With regard to serum albumin and to length of hospital stay (p<0.05), only a significant association could be shown for the MNA (p<0.05). Although the categories of the results were not completely identical for the three tools there were more patients at risk or malnourished according to the MNA (70%) than according to the SGA (45%) or the NRS (40.3%). The direct comparison of the NRS with the MNA and the SGA demonstrated significant differences, especially for the latter (p<0.001). In a relevant percentage of those tested, MNA, SGA, and NRS identify different individuals as malnourished or at risk for malnutrition. Because of its association with relevant prognostic parameters, the MNA is still the first choice for geriatric hospital patients. For those patients to whom the MNA cannot be applied, the NRS is recommended.