Therapies are effective when they have been developed and implemented on a clear understanding of the clinical scenario. Similarly, the long term ESPEN strategy “Fight Against Malnutrition” will be strengthened by a precise appreciation of the current practice of nutritional care. To this end, ESPEN launched the nutritionDay project in 2006, an international one-day audit of nutritional care in hospitals, intensive care units and nursing homes, with a follow up evaluation after 30, 60 and 180 days, respectively. This project aims at offering local and international benchmarks to the health care facilities by comparing their performance and consequently improving their practice. Also, the nutritionDay project provides a unique opportunity to understand the current practice of nutritional care and its impact on outcome, without the bias inherent to clinical trials.