OBJECTIVE: To examine the reliability and validity of the self-report Korean version of Strengths and Difficulties Questionnaire (SDQ-Kr) in the community sample. METHODS: The SDQ-Kr was administered to a large sample of school children and adolescents (n=2814) and youth attendees of a psychiatric clinic (n=385) aged 11-16 years. To examine temporal stability, the same questionnaire was administered to a subsample of 167 school youths five to six weeks after the initial assessment. To examine the reliability, we calculated Cronbach’s alpha coefficients for internal consistency and Pearson’s correlations for test-retest stability. In order to evaluate the factorial structure of the SDQ-Kr items, we conducted an exploratory factor analysis (EFA) with varimax rotation. Finally, discriminant validity was examined by using receiver operating characteristic (ROC) curves employing the area under the curve (AUC) as an index of discriminant ability. RESULTS: Although the internal consistency of some subscales of the SDQ-Kr was somewhat less satisfactory (alpha coefficients; 0.28-0.54) than the English original, coefficients for the total difficulties scores approached sufficient levels (coefficients; 0.69). Other psychometric properties including discriminant validity (AUC for total difficulties and four subscales >0.7) were comparable to those obtained in other language studies. CONCLUSION: The self-report SDQ-Kr exhibited a low level of reliability, indicating that some items need to be further evaluated and revised to improve the psychometric properties. We suggest that the total difficulties score could be used with more confidence for screening possible mental health problems in youths.