BACKGROUND : Patients who may be a danger to themselves or others often are placed on involuntary hold status in the Emergency Department (ED). Our primary objective was to determine if there are demographic and/or clinical variables of involuntary hold patients which were associated with an increased ED LOS. METHODS : Records of ED patients evaluated while on involuntary hold from January 1, 2014 through November 30, 2015 at a suburban acute-care hospital ED were reviewed. Data collected included demographics information, LOS, suicidal or homicidal ideation, suicide attempt, blood alcohol concentration (BAC), urine drug test (UDT), psychiatric disorder, substance use, medical illness, violence in the ED, and hospital admission. Linear regression based on the log of LOS was used to identify factors associated with increased LOS. RESULTS : Two-hundred and fifty-one patients were included in the study. ED LOS (median) was 6 h (1, 49). Linear regression analysis showed increased LOS was associated with BAC (p = 0.05), urine drug test (UDT) (p = 0.05) and UDT positive for barbiturates (p = 0.01). There was no significant difference in ED LOS with respect to age, gender, housing, psychiatric diagnosis, suicidal or homicidal ideation, suicide attempt, violence, medical diagnosis, or admission status. CONCLUSIONS : Involuntary hold patients had an increased ED LOS associated with alcohol use, urine drug test screening, and barbiturate use. Protocol development to help stream-line ED evaluation of alcohol and drug use may improve ED LOS in this patient population.