This is an update of the original Cochrane review published in Issue 2, 2002. Bone marrow transplantation involves administration of toxic chemotherapy and infusion of marrow cells. After treatment, patients can develop poor appetite, mucositis and gastrointestinal failure, leading to malnutrition. To prevent this, parenteral nutrition (PN) support is often first choice but is associated with increased risk of infection. Enteral nutrition (EN) is an alternative, as is addition of substrates.