Objectives: There are currently no data available on drain associated infection occurrence related to the number of drainage days (DD), and thus drain associated infection rates. Therefore, a prospective surveillance study was conducted to determine drain associated infection rates and DD of hospital acquired external ventricular drain (EVD) and lumbar drain (LD) associated meningitis/ventriculitis in a neurosurgery and a neurological intensive care unit. Methods: All patients admitted in 2005 and 2006 were documented. Data on age, admitting diagnosis, type and duration of drain, duration of hospital stay and occurrence of meningitis were recorded and analysed statistically. Results: A total of 1333 patients were included, amounting to 3023 DD. After exclusion of 15 contaminations, a total of 26 cases of meningitis were reported accounting for an overall device associated meningitis rate of 8.6 infections/1000 DD. Infections associated with LD seemed to occur more frequently (19.9/1000 DD) compared with EVD (6.3/1000 DD). The presence of intraventricular blood and previous trauma were significant risk factors for infection (p = 0.003; p = 0.04). Finally, length of stay was significantly longer in meningitis patients (p = 0.0003). Coagulase negative staphylococci were the main pathogen (56%) causing meningitis, followed by Staphylococcus aureus (25%). Conclusions: To the best of the authors9 knowledge, this study represents the first to provide data on EVD as well as LD associated meningitis rates calculated per 1000 DD; a parameter that is well established for other invasive devices such as central venous and urinary tract catheters. However, further prospective studies are needed to investigate the possible risk factors for meningitis.