Background and Issues: Malnutrition such as hypo-proteinemia or sarcopenia often occurs in severe acute stroke patients fed with enteral nutrition. However, it has not been established how to Improve the malnutrition. Leucine, one of essential branched chain amino acids (BCAA), has been shown to trigger muscle growth or stimulate muscle protein synthesis. Purpose: Leucine-enhanced BCAA (LE-BCAA) supplementations can stimulate protein synthesis and improve hypo-proteinemia in severe acute stroke patients. Methods: We included acute stroke patients 1) who were admitted from October 2016 to July 2018, 2) who received enteral nutrition due to severe stroke while their hospitalization 3) whose serum Pre-albumin (Pre-Alb) levels dropped below 20 mg/dl during hospitalization 4) who received LE-BCAA supplementation including leucine more than 1.2 g of leucine per 200 kcal. We measured Biochemical indices for nutrition assessment (Albumin (Alb), Pre-Alb, and Total Cholesterol (T-CHO)) just before and 3 days after starting LE-BCAA. Results: Fifty-six patients met our inclusive criteria and female gender was 35. Their average age was 85 years. Their average body mass index (BMI) on admission was 19.9 kg/m2. When LE-BCAA was started median on the 4 th day after admission, patients’ median Pre-Alb was 12.4 mg/dl, indication severe malnutrition. Then, patients started to tale more than 2.8 g per day of Leucine by LE-BCAA and 3 days later their median Pre-Alb increased up to 13.8 mg/dl, although median Alb level decreased from 2.9 to 2.6 g/dl and median T-CHO level decreased from 164 to 156 mg/dl just before and 3 days after LE-BCAA. Among 56 patients, 41 (73%) had decrease of serum albumin level, 32 (58%) had decrease of serum T-CHO level, whereas 37 (66%) experienced rapid increase of serum Pre-Alb level, this was probably because Pre-Alb was one of rapid turnover proteins. Conclusions: Leucine-enhanced BCAA supplementation can stimulate protein synthesis and achieve rapid improvement of hypoproteinemia in severe stroke patients fed with enteral nutrition.