Intracranial pressure (ICP) monitoring is recommended in patients with a severe traumatic brain injury (TBI) and an abnormal computed tomography (CT) scan. However, there is contradicting evidence about whether ICP monitoring improves outcome. The purpose of this study was to examine the relationship between ICP monitoring and outcomes in patients with severe TBI. From February 2001 to December 2008, a total of 477 consecutive adult (> or =18 years) patients with severe TBI were included retrospectively in the study. Patients who underwent ICP monitoring (n=52) were compared with those who did not (n=425). The primary outcome was hospital mortality. Secondary outcomes were ICU mortality, mechanical ventilation duration, the need for tracheostomy, and ICU and hospital length of stay (LOS). After adjustment for multiple potential confounding factors, ICP monitoring was not associated with significant difference in hospital or ICU mortality (odds ratio [OR] = 1.71, 95% confidence interval [CI] = 0.79 to 3.70, P = 0.17; OR = 1.01, 95% CI = 0.41 to 2.45, P = 0.99, respectively). ICP monitoring was associated with a significant increase in mechanical ventilation duration (coefficient = 5.66, 95% CI = 3.45 to 7.88, P < 0.0001), need for tracheostomy (OR = 2.02, 95% CI = 1.02 to 4.03, P = 0.04), and ICU LOS (coefficient = 5.62, 95% CI = 3.27 to 7.98, P < 0.0001), with no significant difference in hospital LOS (coefficient = 8.32, 95% CI = -82.6 to 99.25, P = 0.86). Stratified by the Glasgow Coma Scale score, ICP monitoring was associated with a significant increase in hospital mortality in the group of patients with Glasgow Coma Scale 7 to 8 (adjusted OR = 12.89, 95% CI = 3.14 to 52.95, P = 0.0004). In patients with severe TBI, ICP monitoring was not associated with reduced hospital mortality, however with a significant increase in mechanical ventilation duration, need for tracheostomy, and ICU LOS.