Central nervous system immune reconstitution inflammatory syndrome (CNS-IRIS) develops in 9 %–47 % of persons with HIV infection and a CNS opportunistic infection who start antiretroviral therapy and is associated with a mortality rate of 13 %–75 %. These rates vary according to the causative pathogen. Common CNS-IRIS events occur in relation to Cryptococcus, tuberculosis (TB), and JC virus, but several other mycobacteria, fungi, and viruses have been associated with IRIS. IRIS symptoms often mimic the original infection, and diagnosis necessitates consideration of treatment failure, microbial resistance, and an additional neurological infection. These diagnostic challenges often delay IRIS diagnosis and treatment. Corticosteroids have been used to treat CNS-IRIS, with variable responses; the best supportive evidence exists for the treatment of TB-IRIS. Pathogenic mechanisms vary: Cryptococcal IRIS is characterized by a paucity of cerebrospinal inflammation prior to antiretroviral therapy, whereas higher levels of inflammatory markers at baseline predispose to TB meningitis IRIS. This review focuses on advances in the understanding of CNS-IRIS over the past 2 years.