Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is an integral part of the treatment strategy for patients with malignant or non-malignant hematological diseases. Clinical outcomes of patients undergoing allo-HSCT have significantly improved in recent decades. However, transplant-related morbidity and mortality remain major issues for allo-HSCT recipients.With regard to nutrition, patients undergoing allo-HSCT are at high risk for malnutrition. It is expected that clinical practice concerning nutritional support in allo-HSCT has been improving in recent decades; however, no data directly support this expectation. One major issue in managing nutritional support during allo-HSCT is the lack of large-scale randomized prospective studies, which leads to a lack of well-established strategies. Accordingly, we need to gather data from studies in non-HSCT and allo-HSCT settings. In some Asia-Pacific countries, a physician's lack of knowledge of nutritional support may impede the application of nutritional support practices recommended by existing guidelines. Another barrier may be the lack of access to an adequately qualified or trained registered dietitian (RD) at allo-HSCT units. Adequate training in the nutritional management of allo-HSCT patients should be provided to all RDs working with HSCT. Herein, we summarize the information on nutritional support in allo-HSCT, focusing on an Asian perspective.