Abstract: Virusencephalitis is characterised by clinical symptoms of a parenchymatous inflammation. In addition, early mental status changes often occur as a result of virusencephalitis, beside focal neurological deficiencies, epileptic seizures, cerebral compression, even coma. Other pathological manifestations of virusencephalitis are disturbances of the neurohumoral and the endocrine system, which are often recognised and treated too late. This case report describes symptoms, treatment, and complications of a 76 year old female in-patient, who was diagnosed with virusencephalitis. The number of lymphocytes in the cerebrospinal fluid was increased to 30 cells per microliter, liquor albumin was 1705 mg/l, liquor sugar was 53 mg/dl and liquor lactat was 1.9 mmol/l. IgM antibodies against herpes viruses were found in the cerebrospinal fluid and distinct contrasting foci were found near the mammillary bodies, hypothalamus, tractus opticus, hypophyseal stalk and right parahippocampal in the magnetic resonance imaging of the head, indicating a focal herpes simplex encephalitis. Within seven days, the following symptoms developed: akinetic parkinsonian syndrome, central diabetes insipidus with hypernatremia and polyuria (6 l/die), hypothyreosis, adrenal insufficiency with adynamia, sopor, hypotension and even hypophyseal coma. Panhypopituitarism was diagnosed after measuring the basal hormone levels (ACTH, TSH, FT3, FT4, Cortisol, Prolactin, LH, FSH, ADH) and conducting the pituitary stimulation test. The severeness of all symptoms was slightly improved after substitution with antidiuretic hormone at 0.4 microgram/die and administration of hydrocortisone at 50 mg/die. Administration of amantadine sulphate at 0.6 g/die and L-dopa at 187.5 mg/die for 14 days resulted in a complete regression of the parkinsonism. After administration of aciclovir at 2.25 g/die for 21 days a complete regression of the clinical symptoms could be reached in connection with a decrease of 90% in number and size of cerebral contrasting foci in the magnetic resonance imaging of the head. Three month after therapy, clinical examination and blood serum analysis revealed persistent panhypopituitarism. The present case report is the first description of a viral infection on of the central nervous system (CNS) in combination with parkinsonism, diabetes insipidus, persistent panhypopituitarism and hyperprolactinemia. Early treatment of viral infections of the brain can improve a patient's prognosis dramatically. Early determination and early treatment of a patient's neurohumoral parameters is therefore critical to prevent or reverse early mental status changes like attention disturbances, alterations of personality and behavior, apathy, and slowed cognition.