Herpes simplex virus type 1 encephalitis (HSE) is the most frequent cause of severe sporadic viral encephalitis. In spite of the advanced modern methods for the treatment of HSE it is still associated with high mortality. Early diagnosis and prompt antiviral therapy with acyclovir are essential to improve prognosis and to prevent severe neurologic sequels.This review summarizes the current knowledge on the pathogenesis, diagnosis, clinical presentation, and treatment of herpes simplex virus type 1 encephalitis. Characteristic features including magnetic resonance imaging (MRI) are illustrated by a typical case.