© 2014, AVES Ibrahim Kara. All Rights reserved.Objective: Malnutrition is a common clinical condition that leads to an increase in morbidity and mortality of critically ill patients. Good nutritional support treatment is essential for the reduction or prevention of malnutrition. In this study, by examining nutritional support therapy in a medical intensive care unit (ICU), we aimed to determine the methods, problems, efficiency, and impact of this therapy on mortality. Material and Methods: Patients hospitalized for more than 72 hours in a medical ICU of a university hospital between January 01, 2010 and June 30, 2010 were included into the study. In this retrospective study, 159 patients were accepted. Patient demographics and nutrition-related data were extracted from hospital and ICU databases, patient files, and records of nursing care. SPSS for Windows, version 15.0 was used to analyze the data. Results: In the study population, the median age was 66 years, and 51% of the patients were men. The median Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II score was 24, and the median nutritional risk screening (NRS) 2002 score was 5. Based on NRS 2002, 99.4% of the patients had malnutrition and needed nutrition support therapy. There was occasional oral intake in 46.0% of the patients. As it was insufficient, enteral nutrition (EN) was delivered in 45%, whereas parenteral nutrition (PN) nutrition was delivered in 88% of the patients. Patients received only 50% of the targeted amount of calories, and only 36% of the targeted amount of proteins on day 3 of nutritional support therapy. The targeted amount of calories was achieved in only 31.4%, while the targeted amount of proteins was achieved in only 33.3% of the patients. In the multivariate analysis, it was demonstrated that mortality was increased by high APACHE II and NRS 2002 scores and modification or interruption of EN and PN, whereas mortality was decreased by oral feeding. Conclusion: It was demonstrated that severe nutritional support was needed in patients admitted to a medical ICU in a university hospital during the frst 6 months of 2010 and that the targeted amount of calories and proteins was achieved in a minority of patients, despite the combined use of EN and PN. It was also demonstrated that mortality was increased by high APACHE II and NRS 2002 scores and modification or interruption of EN and PN.