Citrobacter infection is commonly reported in neonates and immunocompromised patients. Citrobacter koseri (diversus) is an important cause of neonatal meningitis and brain abscess formation. It adults, however, Citrobacter infection with central nervous system involvement is rare, and is usually associated with an underlying disorder. This report describes a 12-y-old previously healthy girl with Citrobacter koseri meningitis. Intravenous treatment with ceftriaxone for 10 d led to complete recovery. Head computed tomography and brainstem-evoked response audiometry were normal. On follow-up, the patient was completely healthy. Previously reported cases of C. koseri meningitis in the adult population were associated with underlying predisposing factors. In this case a normal, healthy adolescent was treated with intravenous ceftriaxone without any of the known neurological complications observed in the neonatal cases.