High-dose chemotherapy followed by autologous bone marrow or peripheral blood progenitor cell transplantation represents a recognized option in the treatment of solid tumors and hematologic diseases. Patients receiving high-dose chemotherapy are traditionally supported with parenteral nutrition with the aim to prevent malnutrition secondary to gastrointestinal toxicity and metabolic alterations induced by the conditioning regimens. Nevertheless, well-defined guidelines for its use in this clinical setting are lacking and there are several areas of controversy.