This retrospective study assessed the parameters of ventriculoperitoneal shunt infection and malfunction found in 129 children with hydrocephalus who had undergone a ventriculoperitoneal shunt placement at Taipei Veterans General Hospital from January 1997 to June 2001. The clinical characteristics and differences among these patients were reviewed to determine the potential predictors of shunt infection and malfunction. Fever (60%, 6/ 10) and seizure (40%, 4/10) occurred significantly more often in the infection group than in the malfunction and control groups (p < 0.05). A higher blood C-reactive protein level was noted in the infection group than in the malfunction and control groups (p < 0.05). Examination of the cerebrospinal fluid of infected patients showed significantly higher white blood cell count and neutrophil count, higher protein concentration, and lower glucose levels compared with the other 2 groups (p < 0.05). However, the number of patients with cerebrospinal fluid eosinophilia was significantly higher in the malfunction group (p < 0.05). The diagnostic usefulness of laboratory parameters in patients with ventriculoperitoneal shunt infection is as follow: cerebrospinal fluid white blood cell count over 100/mm3, 96% specificity and a positive predictive value of 0.55; and cerebrospinal fluid neutrophils over 10%, 90% sensitivity and a negative predictive value of 0.99. In conclusion, Fever, seizure, high blood C-reactive protein, combined with leukocytosis, neutrophil over 10%, low glucose level, and high protein level in the ventricular fluid are factors that may help in distinguishing shunt infection from shunt malfunction.