Considering that beneficial effects of the CCR5 antagonist maraviroc were reported in two patients with PML-associated immune reconstitution inflammatory syndrome (IRIS)—the first with HIV infection [3] and the second with multiple sclerosis [4]—here we describe a patient with advanced HIV infection, who developed PML-associated IRIS and had a fatal outcome despite the addition of maraviroc to suppressive ART. The gene discussed is CCR5; the disease is HIV infectious disease.