Aminoleban^® EN, a nutritional product for patients with liver failure, contains three branched-chain amino acids (BCAAs): L-leucine, L-isoleucine, and L-valine. As BCAAs are extremely bitter, Aminoleban^® EN has a low palatability, which is a major cause of patient noncompliance. Nutrients for liver failure often need to be taken for long periods, and poor medication compliance can cause serious problems, such as encephalopathy. Therefore it is important to suppress the bitter taste of Aminoleban^® EN and thereby improve patient compliance. There are already six different flavoured powders (coffee, green-tea, apple, fruit, plum and pineapple) which can be added to Aminoleban^® EN to reduce its unpleasant taste and smell, but it is possible that other factors, such as temperature, may also improve the palatability of Aminoleban^® EN. In this study, flavours alone significantly decreased the bitterness intensity of Aminoleban^® EN. It was thought that the sweetness and sourness of the flavoured powder would be the main factors involved in decreasing the bitterness. However, low temperature (0—5 °C) decreased the bitterness intensity of Aminoleban^® EN, with or without the flavoured powders, compared with normal room temperature (25—30 °C). The sourness intensity of flavoured powders was not decreased at low temperatures, but the sweetness intensity of some flavoured powders did decrease. These results suggest that sourness can be tasted even at low temperatures. As not only the addition of flavoured powders but also low temperatures can reduce the bitterness of Aminioleban^® EN, the combination of a sour-flavoured powder and a low temperature will improve the palatability of Aminoleban^® EN the most.