Acute urinary retention secondary to Herpes simplex meningitis. We report a case of acute urinary retention in a 24-year-old man with Herpes simplex meningitis without genital lesions. Since the differential diagnosis in young patients who present with acute urinary retention also includes multiple sclerosis, lumbosacral disk herniation, rheumatological disorders and drug intoxication, a thorough history and careful neurological examination are of paramount importance in distinguishing these syndromes. As part of a directed neurological evaluation prompt performance of lumbar puncture is indicated; a lymphocytic pleocytosis is suggestive of herpetic meningitis. Culture of Herpes simplex virus from the cerebrospinal fluid should be attempted. We recommend conservative management only, typically with intermittent catheterization, since bladder function usually normalizes within 10 to 14 days. 