Abstract: Objectives: Our aim was to identify the diagnostic profile of patients classified as ‘false positives’ on two bipolar screening measures; the Mood Swings Questionnaire (MSQ) and the Mood Disorders Questionnaire (MDQ).Methods: A total of 1534 patients attending the Black Dog Institute Depression Clinic completed the MSQ-46, and a smaller subset of 852 completed the MDQ. All patients underwent clinical assessment by one or more Institute psychiatrists.Results: Using clinical assignment (i.e. bipolar vs. unipolar) as the criterion measure for assessing the screening measures, the overall agreement rates were 84% for the MSQ-46 and 74% for the MDQ. Patients identified as ‘false positives’ were most likely to be clinically diagnosed as having a unipolar non-melancholic depression (37% for MSQ-46; 46% for MDQ), or a primary anxiety condition with secondary non-melancholic depression (19% for MSQ-46; 15% for MDQ). In addition, within the unipolar non-melancholic group, 46% of the MSQ-46 assigned false positives and 63% of the MDQ assigned false positives had co-morbid anxiety conditions.Conclusions: These findings suggest that patients with anxiety conditions account for a significant proportion of false positive diagnoses on bipolar screening tests — a finding that should be conceded in the development and refinement of such screening measures and in clinical assessment of the possibility of a bipolar disorder.