Immunotherapies such as immune checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor (CAR) T-cell therapy are emerging as new treatments for relapsed and/or refractory hematological malignancies. CAR T-cell therapy has attracted attention as a potentially curative treatment for patients incurable by chemotherapy. However, appropriate management is required to avoid serious complications specific to CAR T-cell therapy, such as cytokine release syndrome (CRS), neurotoxicity (ICANS), hypogammaglobulinemia and prolonged cytopenia, as well as post-treatment infections caused by suppressed immune function.