Since its initial discovery in the 1940s, Mycoplasma pneumoniae has emerged as a commonly diagnosed bacterium, gaining recognition as a global cause of primary atypical pneumonia. M. pneumoniae is a significant cause of upper and lower respiratory tract infections worldwide, predominantly among children. Encephalitis is one of its most severe extrapulmonary manifestations and may result in significant neurological sequelae. We present a case of M. pneumoniae encephalitis and introduce a diagnostic tool to support its diagnosis.