Purpose: The purpose of this study is to compare the NST (Nutrition Support Team) group with the non-NST group on the basis of nutritional guidelines and to examine how the NST`s intervention influences clinically important end points of critically ill patients. Methods: Between January 2009 and December 2009,161 patients in the ICU (Intensive Care Unit) and who were provided PN (Parenteral Nutrition) were included. SAS (Statistical Analysis System) was used for the analysis. Results: In this study, 161 patients were administered PN for 7.3±6.7 days and 8.7% of the patients were provided support by NST. The number of PN prescriptions was 235 and among them, only 7.2% were conducted according to the recommendations of the NST. Both of the groups (the NST and non-NST groups) had a marked malnutrition level of 1 when admitted to the ICU. During the hospitalization, the malnutrition level was increased (NST: P=0.03,non-NST: P＜0.01). The NST group was provided macronutrients more often than the non-NST group under the guidelines. Supplement of micronutrients (vitamins) was significantly different between the two groups (82.4% vs.32.6%, respectively). There was no statistical difference in the administration of amino acid by dialysis between the dialysis and non-dialysis patients. Hyperglycemia was the most common complication related to PN for both of the groups. Also, hepatic dysfunction occurred in the NST group more often than that in the non-NST group (35.7% vs. 12.3%, respectively, P=0.03). Sepsis was associated with hepatic dysfunction and among the 5 patients with hepatic dysfunction in the NST group, 3 patients were sepsis. Conclusion: Regardless of NST consultation, most patients were provided PN under the guideline, but the administration of amino acids to the dialysis patients and the administration of micronutrients were inappropriate in the non-NST group. Therefore, it is necessary to make efforts for providing proper nutritional support to patients through more systematic NST activities and advertisement.(KJPEN 2010;3(1):54-60)