BACKGROUND: This study was done to validate the three single questions about binge drinking for identifying problem drinkers. METHODS: Two hundred sixty-one patients (133 men) were interviewed by family physicians for the presence of problem drinking which was defined as at-risk drinking or alcohol use disorders according to the National Institute on Alcohol Abuse and Alcoholism (NIAAA) guideline and Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria. The three single questions (the largest amount of drinking in a day; days of drinking 1.5 bottle [1 bottle in women] or more of Soju [Korean alcoholic beverage, 56 g of alcohol/bottle]; and days of getting drunk during the recent 3 months) were validated against the interview results. RESULTS: Among 261 interviewees, 31.4% were at-risk drinkers, 30.2% had a current alcohol use disorder, and 36.8% had either or both conditions. The first question, considering 4 drinks or more for men and 3 drinks or more for women as positive, showed a sensitivity of 93.8% and specificity of 75.0% in men, and 86.6% and 86.7% in women, respectively. The second question with cut-point of 1 in both gender showed 81.3% and 86.5% in men, respectively and 80.0% and 89.4%, respectively in women. The third question with cut-point of 3 in both gender showed 61.7% and 92.3% in men, respectively and 46.7% and 91.2%, respectively in women. The area under the Receiver Operating Characteristic curve of the first question was 0.937 in men and 0.970 in women, for the second question, 0.906 and 0.915, and for the third question, 0.768 and 0.764, respectively. CONCLUSIONS: The first question (the largest amount of drinking in a day during the recent 3 months) and the second question (days of drinking 1.5 bottle [1 bottle in women] or more of Soju during the recent 3 months) were considered useful in detecting problem drinkers.