We reviewed cerebrospinal fluid (CSF) shunt infections treated in the Royal Children's Hospital, Melbourne from 1981 to 1991. Forty-one episodes of CSF shunt infection were found after 900 shunt operations, an infection rate of 4.5%. Clinical symptoms were nonspecific in 31.7% of episodes, and in 17.1% of episodes the initial CSF sample was normal on microscopy and biochemistry, although a pathogen was isolated on culture. Most episodes occurred within 4 months of the last operation on the shunt, the exception being infections caused by Haemophilus influenzae. Four patients died during treatment, but none could be attributed to infection alone. Treatment of suspected CSF shunt infection should not be withheld because of lack of firm clinical diagnosis or normal CSF microscopy, and episodes occurring more than 4 months after the last operation on the CSF shunt should receive antibiotic cover for H. influenzae.