Current clinical data show that every third hospitalized patient in Germany is malnourished. This indicates a need for mandatory nutrition status screening and evidence based clinical nutrition. The cost-effectiveness-estimate of this concept has not yet been evaluated by a diagnosis based severity-of-disease risk-adjustment. NUTRICORE is the first study worldwide, using the predictive scale of Disease Staging to get valid data on risk-adjusted clinical and economic outcomes in the field of clinical nutrition research on large patient populations (>10,000). OBJECTIVES: To show a positive correlation of an evidence based clinical nutrition concept on clinical and economic outcomes in malnourished hospitalized patients by risk-adjustment on severity of disease and corresponding cost-effectiveness-analysis. METHODS: NUTRICORE SP1 is a prospective controlled interventional multicenter based clinical trial with more than 10.000 patients from German Hospitals. The nutrition status of each patient is screened and combined with clinical data, utilization data and direct costs on the basis of clinical homogenous patient clusters. The risk adjustment scales can be run by routine data sets from German inpatient G-DRG system 2006. In the control period starting in June 2006 the effects of usual nutrition care are documented. Starting the intervention period in October 2006 an implementation of an interdisciplinary evidence-based guideline for screening and clinical nutrition will be introduced in each participating hospital. RESULTS: NUTRICORE SP1 has been piloted in two 600-bed-hospitals in Germany during 2005, showing a significant reduction of costs for clinical nutrition by €152,544.00 per year for a risk-adjusted patient population of €38,004 cases in total. CONCLUSION: The study NUTRICORE SP1 is intended to show significant clinical improvements and significant cost-effectiveness by the implementation of an evidence based nutrition concept within clinical homogenous patient groups leading to reduction of Length of Stay (LOS), Inpatient Mortality, Complications-of-Care, hospital readmission.