Malnutrition is common in liver cirrhotic patients who will undergo liver resection or liver transplantation. A precise evaluation of their nutrition status is thus difficult because of the presence of ascites and the edema caused by their impaired protein synthesis. Both perioperative enteral and parenteral nutrition have benefits in reducing the morbidity and mortality of liver surgery, and in general, oral nutrition supplements are recommended. Branched-chain amino acids (BCAAs) promote protein and glycogen synthesis and regulate immune system function. Synbiotics, a combination of pro- and prebiotics, is reported to enhance immune responses. Oral nutrition support with BCAAs, synbiotics, and an immune-enhancing diet have a beneficial effect on preventing the perioperative infections associated with hepatic resection or liver transplantation.