The outbreak of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), generated an unprecedented global health and social emergency. Despite many efforts from clinicians to develop effective anti-COVID-19 treatment protocols, no specific therapy is currently available. Among anti-viral agents, convalescent plasma (CP) from recovered patients is the object of intense research following the first positive reports in severe COVID-19 patients. Passive immunotherapy the rationale to provide higher benefits in COVID-19 patients with humoral immune deficiencies, such as those with solid and hematologic cancers, patients with primary and acquired immunodeficiencies, and recipients of solid organ and hematopoietic stem cell transplants. The aim of this narrative review will be to critically discuss the literature evidence on CP use in these categories of patients. Copyright © 2021 Elsevier Ltd. All rights reserved.