‘Query encephalitis’ is a common neurological consultation in hospitalised patients. Identifying the syndrome is only part of the puzzle. Although historically encephalitis has been almost synonymous with infection, we increasingly recognise parainfectious or postinfectious as well as other immune-mediated causes. Encephalitis must also be distinguished from other causes of encephalopathy, including systemic infection, metabolic derangements, toxins, inherited metabolic disorders, hypoxia, trauma and vasculopathies. The paper discussed in this podcast reviews the most important differential diagnoses (mimics) of patients presenting with an encephalitic syndrome and highlight some unusual presentations (chameleons) of infectious encephalitis.