Objective: To examine the ability of medical students to identify hazardous drinkers using screening tools recommended in clinical practice. Design: Observational cross-sectional study. Setting: Faculty of Medicine of Castilla-La Mancha, Spain. Method: The medical students learnt to use Alcohol Use Disorders Identification Test (AUDIT) and Systematic Interview of Alcohol Consumption (SIAC) questionnaires. After training with these instruments, the medical students anonymously assessed their own alcohol consumption. Results: The medical students easily learnt to assess alcohol consumption using both instruments, as alcohol consumption was quantified correctly in 95.8% of cases. The questions asked by the students were referred to the questionnaires scoring procedure, quantification of the grams of alcohol consumed and conversion of grams of alcohol into standard drink units (SDUs). In total, 50.9% of men and 48.1% of women fulfilled criteria of excess alcohol consumption, and the global percentage of these drinkers corresponded to 49.5% (95% confidence interval [CI]: 42.4%--56.6%). Alcohol consumption of at least 28 SDUs/week in men and 17 SDUs/week in women was detected in 16.8% of participants. Conclusion: Because of the simplicity of the instruments used to detect hazardous drinking, these can be learnt from the very first stages of medical training, thus encouraging students to initiate clinical prevention tasks, and increase their awareness of both their own and others' hazardous behaviour.