Introduction: Excessive consumption of alcohol is associated with harm and responsible for up to 30% of emergency department (ED) visits. ED visits and length of stay (LOS) related to alcohol intoxication have increased over the last decade. The objective of this study was to compare the ED LOS of alcohol intoxicated and non-alcohol intoxicated patients presenting to the ED with acute head injury. Methods: This was a nested cohort analysis of patients screened for enrollment in a randomized controlled trial assessing minor traumatic brain injury (MTBI) discharge instructions in the ED of an academic tertiary care hospital (annual census 65,000). Patients aged 18 to 64 years presenting to the ED with a Canadian Emergency Department Information System (CEDIS) chief complaint of a head injury or suspected concussion occurring within 24 hours were eligible for study inclusion. Patients were identified as acutely intoxicated by their treating clinical providers. ED LOS for patients acutely intoxicated and those not intoxicated was compared using a Mann-Whitney U test using the Hodges-Lehmann method. Proportional differences were assessed using chi-square statistics. Results: A total of 164 patients were included in the analysis, 46 (28.0%) intoxicated and 118 (72.0%) not intoxicated. Median (IQR) ED LOS was 2.9 (1.5, 6.6) hours for intoxicated and 1.8 (1.3, 2.9) hours for non-intoxicated patients (Δ1.1 hours; 95% CI: 0.4, 1.8). Arrival by ambulance was higher in the intoxicated (73.9%) compared to the non-intoxicated (29.7%) group (Δ44.3%; 95% CI: 27.6, 57.1). Patients were more likely to have experienced assault in the intoxicated (34.8%) compared to the non-intoxicated (6.8%) group (Δ28.0%; 95% CI: 14.5, 42.8). There no difference in the proportion of patients who arrived after daytime hours, had a brain computed tomography, received analgesia in the ED, had another traumatic injury or had a history of psychiatric illness. Conclusion: One third of patients screened for a randomized controlled trial for MTBI were deemed ineligible for study inclusion due to acute alcohol intoxication. Alcohol intoxication was associated with prolonged ED LOS. Future studies specifically aimed at identifying factors that impact care on this frequent ED patient population are needed.