Herpes simplex encephalitis is a rare complication of Herpes virus infections. Innate immune mechanisms are the first line of defence encountered by invading infectious agents. A 41-year-old man was admitted to the neurology department with the complaints of fever, headache, vertigo, tinnitus and ataxia. His first brain Magnetic Resonance Imagine showed nodular lesions in the medulla oblongata and the second showed a new left occipital lobe lesion in addition. In sera, Herpes Simplex Virus IgG and M values were positive and liver enzymes were found to be elevated. His diagnosis was Herpes encephalitis with liver involvement. CD19, CD20, CD21, CD22, CD35 receptors were found to be diminished. In this case we want to address that one of the causes of Wallenberg's lateral medullary syndrome can be Herpes simplex virus-1 and probable immune system deficiency can be researched.