Postoperative early enteral nutrition or early oral ingestion is recommended in surgical patients. In this situation, this study examined the role of parenteral nutrition in the postoperative period in patients undergoing elective surgery. The nutritional status should be assessed before surgery and in the case of malnutrition, nutritional support should be provided before surgery to obtain good results. More than 2 weeks of insufficient nutritional support after surgery may worsen the patient’s progress. Therefore, it is recommended to start nutritional care if the oral intake is not appropriate until 7 days or 5 to 7 days after surgery. Enteral nutrition is related to the quick restoration of the bowel function and reduction of infection-related complications. Therefore, enteral nutrition has priority. On the other hand, depending on the patient’s condition, it may not be possible to perform enteral nutrition, and the uniform implementation of the early enteral nutrition may be a burden to the patient. Parenteral nutrition has the advantage that it can supply nutrition without being affected by the intestinal condition, and it can be calculated to supply as much energy as required. The situation, where parenteral nutrition is required after elective surgery, could be summarized as 1) the patients who underwent nutritional therapy before surgery and could not tolerate oral intake or enteral nutrition after surgery. or 2) in the case where enteral nutrition did not satisfy 50% of the demand at 7 days after surgery, and it is judged that this situation should continue for 7 days.