Purpose: The purpose of this study was to determine whether poor preoperative nutritional status in elderly patients exhibited a negative influence on postoperative clinical outcomes. Methods: The medical records of 645 elderly patients were examined retrospectively. The patients had undergone major surgery between January 2017 and January 2018. Their nutritional status was measured using the Nutritional Risk Screening 2002. The data were analyzed using the chi-squared test, the Mann-Whitney U test, logistic regression, linear regression, Cox proportional hazards regression, and the Kaplan-Meier analysis. Results: Preoperative malnutrition was found in 73 patients (11.3%). Poor preoperative nutritional status was significantly associated with pressure ulcers, length of hospitalization, discharge to patient care facilities rather than home, and mortality rate at three months. Conclusion: Preoperative malnutrition in elderly patients was associated with negative postoperative clinical outcomes. These results indicate that an effective nutritional program before surgery can lead to a more rapid postoperative recovery.