Liver cirrhosis is frequently accompanied by malnutrition and hypoalbuminemia, which in turn commonly induces ascites in patients with liver cirrhosis. Ascites leads to abdominal distention and appetite loss, resulting in a deteriorated quality of life (QOL). Administration of branched-chain amino acid (BCAA)-rich supplements reduces hepatic encephalopathy and malnutrition. In addition, BCAAs by themselves up-regulate albumin synthesis through an increase in Fisher's ratio. Thus, in patients with liver cirrhosis, BCAA-rich supplements seem to be effective at reducing ascites and improving the QOL. Here, we report the case of a 58-year-old Japanese man with liver cirrhosis with severe ascites and peripheral edema. The hepatic function of the patient was classified as Child-Pugh grade C. To reduce protein-energy malnutrition, BCAA-rich supplements were administered as a late evening snack as part of a regimen including 2000 kcal/day (32.5 kcal/kg/day) of total energy and 83.5 g/day (1.3 g/kg/day) of total protein intake. Eight weeks after admission, ascites and edema had decreased. Nutritional status also improved from the time of admission to discharge; the serum BCAA level increased from 365.4 to 450.2 µmol/l. Furthermore, the ratio of BCAAs to tyrosine (BTR) increased from 1.70 to 3.65. We also evaluated the effects of nutritional therapy on the patient's QOL using the Medical Outcomes Study 36-Item Short-Form Health Survey upon admission and at discharge. All subscores showed marked improvement and reached a level greater than the Japanese norm with nutritional treatment. In conclusion, BCAA supplementation not only reduced ascites, but also improved the QOL in a patient with liver cirrhosis.