Purpose: The objective of this study was to develop a new nutrition screening tool for quality improvement of the nutritional care process in an acute care hospital with a 2,000-bed capacity. Methods: To evaluate the current nutrition screening tool, we first examined 435 patients (274 men, aged 59.0±12.2 years). In the second step, the nutritional status of 387 patients (215 men, aged 57.5±13.3 years) was assessed by the scored patient-generated subjective global assessment (PG-SGA) tool. Variables such as age, body mass index (BMI), plasma albumin concentration, weight change, food intake change, and disease severity were analyzed to select indices for developing a new Severance nutrition screening index (SNSI). Results: The current nutrition screening tool had a poor correlation with the PG-SGA (κ=0.180, P＜0.0001). The SNSI was calculated as follows: SNSI = 1.5×albumin＋ 1.0×BMI＋4.5×intake change＋1.5×weight loss (for albumin＜ 3.0, BMI＜20, and decreased intake and weight loss＞5% of usual body weight). The SNSI showed a sensitivity of 90.5%, a specificity of 90.7%, and a high correlation (κ=0.628, P＜0.0001) with the PG-SGA. Conclusion: The SNSI appears to be a valid and useful nutrition screening tool to determine the nutritional risk of patients in acute care hospitals.