Résumé : OBJECT: The authors undertook a study to analyze the risk factors for ventriculostomy-related infections (VRIs) in critically ill patients and their relation with outcome. METHODS: Demographic, clinical, laboratory, and microbiological data were collected from all 638 consecutive adult patients in whom an external ventriculostomy catheter was placed for monitoring during a 6-year period; patients were treated in a 31-bed intensive care unit (ICU) of a teaching hospital. Of 3726 cerebrospinal fluid (CSF) culture samples analyzed, 1348 (217 patients) showed bacterial growth; of these 97 (obtained in 58 patients [9%]) were considered to represent an infection, 106 (in 68 patients [11%]) colonization, and 145 (in 91 patients [14%]) contamination. Hence, a VRI was diagnosed in 58 (9%) of 638 patients. There were no significant differences in Acute Physiology and Chronic Health Evaluation II score, Glasgow Coma Scale score, and mortality rate, but patients with a VRI stayed longer in the ICU than those without one (p = 0.02). The duration of ventriculostomy monitoring was longer in patients with VRI (median 15 and 9 days, respectively; p = 0.02). Although the daily drained volume of CSF was higher after onset of the infection than before infection in patients with VRI (124 +/- 36 and 85 +/- 14 ml/day, respectively), the need for ventriculoperitoneal shunt placement was no more common in those with VRI than in those without (12 and 15%, respectively; p = 0.2). Multivariate logistic regression revealed that subarachnoid hemorrhage (SAH), intraventricular hemorrhage (IVH), craniotomy, and coinfection were risk factors for VRIs. CONCLUSIONS: In this large series of patients, VRI was associated with a longer ICU stay, but its presence did not influence survival. A longer duration of ventriculostomy catheter monitoring in patients with VRI might be due to an increased volume of drained CSF during infection. Risk factors associated with VRIs are SAH, IVH, craniotomy, and coinfection.