OBJECTIVE: This study reports the frequency of alcohol use and associated tobacco and drug use among emergency department (ED) patients, in order to increase physician awareness and treatment of women and men seeking care in ED settings. METHOD: All adults seen in the ED at the University Hospital in Lausanne, Switzerland, between 11 AM and 11 PM were screened by direct interview for at-risk drinking, tobacco use, drug use, and depression during an 18-month period. RESULTS: A total of 8,599 patients (4,006 women and 4,593 men) participated in the screening procedure and provided full data on the variables in our analysis. The mean age was 51.9 years for women and 45.0 years for men; 57.5% (n = 2,304) of women and 58.5% (n = 2,688) of men were being treated for trauma. Based on guidelines of the National Institute on Alcohol Abuse and Alcoholism, 13.1% (n = 523) of the women were at-risk drinkers, 57.3% (n = 2,301) were low-risk drinkers, and 29.6% (n = 1,182) were abstinent. Among men, 32.8% (n = 1,507) met criteria for at-risk drinking, 51.8% (n = 2,380) met criteria for low-risk drinking, and 15.4% (n = 706) were abstinent. Younger individuals (ages 18-30) had significantly higher rates of episodic heavy drinking episodes, whereas at-risk older patients were more likely to drink on a daily basis. A binary model found that women and men who drank at at-risk levels are more likely to use tobacco (odds ratio [OR] = 2.48, 95% confidence interval [CI]: 2.0-3.08) and illicit drugs (OR = 5.91, CI: 3.32- 10.54) compared with abstinent and low-risk drinkers. CONCLUSIONS: This study supports systematic alcohol screening of women and men seen in EDs and suggests that patterns of alcohol and drug use vary by age and gender.