The Mini Nutritional Assessment (MNA) is a simple tool, useful in clinical practice to measure nutritional status in elderly persons. From its validation in 1994, the MNA has been used in hundreds of studies and translated into more then 20 languages. It is a well-validated tool, with high sensitivity, specificity, and reliability. An MNA score > or = 24 identifies patients with a good nutritional status. Scores between 17 and 23.5 identify patients at risk for malnutrition. These patients have not yet started to lose weight and do not show low plasma albumin levels but have lower protein-calorie intakes than recommended. For them, a multidisciplinary geriatric intervention is needed, which takes into account all aspects that might interfere with proper alimentation and, when necessary, proposes therapeutic interventions for diet or supplementation. If the MNA score is less than 17, the patient has protein-calorie malnutrition. It is important at this stage to quantify the severity of the malnutrition (by measuring biochemical parameters like plasma albumin or prealbumin levels, establishing a 3- day record of food intake, and measuring anthropometric features like weight, BMI, arm circumference and skin folds). Nutritional intervention is clearly needed and should be based on achievable objectives established after a detailed comprehensive geriatric assessment. The MNA has been shown to be useful for nutritional intervention follow-up as well. The MNA can help clinicians design an intervention by noting where the patient loses points when performing the MNA. Moreover, when a nutritional intervention is successful, the MNA score increases. The MNA is recommended by many national and international clinical and scientific organizations. It can be used by a variety of professionals, including physicians, dietitians, nurses or research assistants. A short screening version (MNA-SF) has been developed, which, if positive, indicates the need to complete the full MNA. It takes less than 4 minutes to administer the MNA-SF and between 10 and 15 minutes for the full MNA.