Background The impact of alcohol use has been widely studied and is considered a public health issue. The National Institute on Alcohol Abuse and Alcoholism (NIAAA) recommends Screening and Brief Intervention and Referral Treatment (SBIRT) but the actual practice in the Emergency Department (ED) is deviated due to limited provider time and financial resources. Objectives To assess the effectiveness of alcohol screening using Computerised Alcohol Screening and brief Intervention (CASI) compared to alcohol screening by triage nurse during Medical Screening Examination (MSE) in the ED. Methods Retrospective review of CASI/MSE database from January 2008 through December 2009, collected in the tertiary, level I Trauma ED was performed. Inclusion criteria included age ≥18, and completion of both the MSE and CASI. We analysed the database by comparing age, gender, primary language (English, Spanish), and Alcohol Use Disorders Identification Test (AUDIT) scores using McNemar's analysis. Results Data was available for 5835 patients. CASI showed an increase in detection of at-risk drinking over MSE across all ages, gender, and primary language with statistically significant. MSE found 2.5% at-risk drinkers while CASI found 11.5% at risk drinkers (OR 8.88, 95%CI 6.89 to 11.61). Similar results were found in 18–20-year-old patients. MSE identified 1.7% at-risk drinkers and CASI reported 15.94% (OR 19.33, 95% CI 6.29 to 96.74). Significance CASI increased detection of at-risk alcohol drinkers compared with MSE across all ages, gender, and primary language. CASI is a promising innovative method for alcohol screening in the ED for the adult population including under-aged drinkers.