Thirteen of 29 patients with meningitis had a complicating ventriculitis (white blood cell count > 200/cu mm or positive ventricular fluid culture), including eight of 12 neonates. Ventriculitis should be considered a brain abscess and treated with the direct instillation of antibiotics. Periodic irrigation and drainage may be necessary. Very high antibiotic levels can be obtained in the ventricular fluid using the recommended dose schedule. A Salmon-Rickham ventriculostomy reservoir was placed in the lateral ventricle to obviate repeated puncture of the brain. Seven of ten patients with ventriculitis given antibiotics intraventricularly and systemically are normal including four of six neonates. The ratio of head circumference to cerebral mantle is used as a rough estimate of the ventricular fluid volume to aid in selecting the proper antibiotic dose.