OBJECTIVE: The objective of this study was to identify factors associated with the decision to withdraw mechanical ventilation from patients in a neurology/neurosurgery intensive care unit. Specifically, the following factors were considered: the severity of the neurologic illness, the healthcare delivery system, and social factors. DESIGN: Retrospective analysis of prospectively collected clinical database. SETTING: Neurology/neurosurgery intensive care unit of a large academic tertiary care hospital. PATIENTS: Patients were 2,109 nonelective admissions to the neurology/neurosurgery intensive care unit who received mechanical ventilation over a period of 82 months. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The average age was 56 +/- 19.7 yrs, 53% were male, and 81% were functionally normal before admission. The median Glasgow Coma Scale score was 14, the average Acute Physiology and Chronic Health Evaluation II severity of illness score was 13.5 +/- 8.3, and probability of death was 18.2 +/- 22.0%. Mechanical ventilation was withdrawn from 284 (13.5%). Factors that were independently associated with withdrawal of mechanical ventilation were as follows: more severe neurologic injury [admission Glasgow Coma Scale score (odds ratio 0.86/point, confidence interval 0.82-0.90), diagnosis of subarachnoid hemorrhage (odds ratio 2.44, confidence interval 1.50-3.99), or ischemic stroke (odds ratio 1.72, confidence interval 1.13-2.60)], older age (odds ratio 1.04/yr, confidence interval 1.03-1.05), and higher Acute Physiology and Chronic Health Evaluation II probability of death (odds ratio 1.03/%, confidence interval 1.02-1.04). Mechanical ventilation was less likely to be withdrawn if patients were African-American (odds ratio 0.50, confidence interval 0.36-0.68) or had undergone surgery (odds ratio 0.44, confidence interval 0.2- 0.67). Marital status, premorbid functional status, clinical service (neurology vs. neurosurgery), attending status (private vs. academic), and type of health insurance were not associated with decisions to withdraw mechanical ventilation. CONCLUSIONS: We conclude that decisions to withdraw mechanical ventilation in the neurology/neurosurgery intensive care unit are based primarily on the severity of the acute neurologic condition and age but not on characteristics of the healthcare delivery system. Care is less likely to be withdrawn from African-American patients or those who had surgery.