Twelve patients with shunt infection occurring more than 6 months following shunt implantation or revision were identified and their charts reviewed. These cases were accumulated over a 9-year period, and delays from shunt surgery to detection were as long as 11 years. For 5 patients, no antecedent infection or surgery could be identified as a presumptive cause of the shunt infection. Propionibacterium species and Staphylococcus epidermidis species were the most common organisms identified. The risk of late onset of infection at this institution is less than 1% per year.