Brentuximab vedotin (BV) is an anti-CD30 monoclonal antibody-drug conjugate that was approved in 2011 for the treatment of patients with anaplastic large cell and Hodgkin lymphomas. The product label indicates that 3 patients who were treated with BV developed progressive multifocal leukoencephalopathy (PML), a frequently fatal JC virus-induced central nervous system infection. Prior immunosuppressive therapy and compromised immune systems were postulated risk factors. In the current study, the authors reported 5 patients who developed BV-associated PML, including 2 immunocompetent patients.