Objectives: The aims of the study were to validate the Turkish version of the Mood Disorder Questionnaire (MDQ) as a screening tool and to determine its optimum cut-off value for bipolar disorder,Methods: Validation of the Turkish version of the MDQ was conducted on a sample of 309 consecutive patients who attended the psychiatry outpatient unit of 2 different university hospitals. The Structured Diagnostic Interview for DSM-IV Axis I Disorders (SCID) was used as a gold standard test and receiver operating characteristic (ROC) analysis was used to evaluate test performance of the MDQ.,Results: In all, 36 (11.7%) patients received a diagnosis of bipolar disorder (type I and //, and bipolar disorder not otherwise specified), 185 (86.1%) were diagnosed as having at least one Axis I psychiatric disorder other than bipolar disorder and 7 (2.2%) had no psychiatric disorder according to SCID results. Sensitivity and specifity results indicated that the best Turkish MDQ cut-off point was 7 (sensitivity: 0.64; specifity: 0. 77), the cut-off point 5 had 0.81 sensitivity and 0.53 specifity, and the cut-off 6 had 0. 75 sensitivity and 0.63 specifity.,Conclusion: The Turkish MDQ has satisfactory psychometric properties for screening bipolar disorder The psychometric properties of the Turkish MDQ and its ease of use make it a useful tool for screening bipolar disorders, though further populotion-based research is required to confirm these results.