Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Altered immunocompetence is defined by loss or qualitative deficiency in cellular or humoral immune components that occurs as a result of a disease process or a disease therapy. Vaccines may be less effective during the period of altered immunocompetence. HSCT is often associated with a loss or diminution of protective immunity against pathogens targeted by childhood immunizations. As a result, there has been interest in vaccinating patients in the post transplantation period to reduce the risk of infection Nonetheless; incompetent immunity may hamper the efficacy of immunization for such patients by, particularly in the early post transplantation period. Many recommendations, based on the published literature, have been available regarding the immunization of patients following HSCT and patients with altered immunocompetence. This work should be useful to professionals working in the field of Vaccinations in Haematological Related Diseases and Haematopoietic Stem Cell Transplantation.