A 6-week-old infant admitted to the University Hospital of the West Indies with hydrocephalus later developed ventriculitis. A heavy growth of Flavobacterium odoratum susceptible to gentamicin and cefotaxime was recovered from the ventricular fluid. Since intraventricular therapy was envisaged, a Pudenz reservoir was installed and ventricular fluid aspirated every 24 h to monitor treatment. Initial therapy consisted of intravenous cefotaxime, 50 mg/kg q.i.d. for 4 days. No significant reduction in the number of organisms in the ventricular fluid was achieved with this regimen. Intravenous therapy was therefore discontinued. On day 5 intraventricular therapy began with 5 mg cefotaxime 24 h for 6 days, followed by 1 mg/24 h for 4 days. Daily monitoring of intraventricular fluid indicated a high degree of antibacterial activity with rapid elimination of bacteria. Ventricular fluid remained sterile 10 days after therapy stopped. The Pudenz reservoir was removed, a ventriculoperitoneal shunt installed, and the patient discharged from hospital 4 days later without noticeable sequelae.