Branched-chain amino acids (BCAA) supplementation is used to promote protein synthesis in different clinical conditions in which proteolysis is increased. In addition, lower plasma BCAA levels have been related to an increased risk of hepatic encephalopathy in liver cirrhosis. In this article we will review the role of supplementation with BCAAs and BCAA derivative β-hydroxy-β-methylbutyrate (HMB) in liver cirrhosis, focusing on nutritional and clinical effects. Evidence shows that BCAA supplementation slightly increases muscle mass and body mass index, with an upward trend in muscular strength and no change in fat mass. Moreover, BCAA supplementation improves symptoms of hepatic encephalopathy, and is indicated as second-line therapy. The evidence is more limited for BCAA derivatives. HMB supplementation appears to increase muscle mass in chronic diseases associated with cachexia, although this effect has not yet been clearly demonstrated in liver cirrhosis studies. To date, HMB supplementation has no clinical indication in liver cirrhosis.