This line of research started at the end of 1998, focusing on patients undergoing allogeneic haematopoietic stem cell transplantation (allo-HSCT). The research group, with nearly 30 years of experience in the field, has established itself as a leading group in the national and international area, as evidenced by the fact that more than 100 papers have been published on this subject in international journals of medium-high impact. In collaboration with the Hospital’s Hematology Service and i the Spanish Hematopoietic Transplant Group (GETH), the Immunobiology of CMV infection research line has contributed to defining a viremia risk profile, potentially deleterious in these patients, and to improve the early treatment strategy for CMV viremia, with the ultimate goal of preventing the development of organic and tissue viral disease.