To assess the predictive effect of key individual-level characteristics to identify cases of alcohol use problems among patients visiting an emergency room.The study sample was composed of 371 people attending an emergency room in a public hospital in Lima, Peru, during a period of seven complete days in January, 2005. For data gathering, we used a questionnaire for demographic information, the SIDUC/CICAD for recent use (i.e., in the last 6 hours) of psychoactive substances before arriving to the emergency room, and the AUDIT, to identify alcohol use problems in the last year. Univariate and multivariate logistic regression models were used to estimate the predictive effect of age, sex, area of attention in the emergency room, presence of physical injuries and recent use of alcohol.The odds of being a case of alcohol use problem for males is 26 times the odds of having that problem for females (p-value<0,001). Stratified analysis by sex and adjusted by age and area of attention in the emergency room, showed that males who had recent use of alcohol were more likely of having alcohol use problems as compared to those who did not have recent alcohol use (OR=5.2; 95% CI: 2.4 - 11.5; p<0,001), while for females such an association did not exist.These results support screening initiatives for those males who have recent alcohol use before arriving to an emergency room in order to identify cases of alcohol-related problems and refer them for an appropriate counseling or medical treatment.