Herpes virus reactivation is a well-known phenomenon rarely described in neurosurgery. We report a case of type 2 herpes simplex virus reactivation following neurosurgery of the posterior fossa. Cerebrospinal fluid analysis revealed a lymphocytic pleocytosis of over 200  10⁶/l. Viral reactivation should be considered in patients with fever, meningism and extended hospital admission following neurosurgical procedures.