Background: Anxiety and depression are common problems following traumatic brain injury (TBI), warranting routine screening. Self-report rating scales including the Hospital Anxiety and Depression Scale (HADS) are associated with depression and anxiety diagnoses in individuals with TBI. The relationship between individual HADS symptoms and structured clinical interview methods (SCID) requires further investigation, particularly in regard to identifying a small number of key items that can potentially be recognised by clinicians and carers of individuals with TBI. Methods: 138 individuals sustaining a complicated-mild to severe TBI completed the HADS, and the Structured Clinical Interview for DSM-IV, Research Version (SCID) at 12-months post-injury. The associations between individual HADS items, separately and in combination, as well as overall depression and anxiety subscale scores, and SCID-diagnosed depressive and anxiety disorders were analysed. Results: CART (Classification and Regression Tree) analysis found HADS depression item 2 “I still enjoy the things I used to enjoy” and a combination of two anxiety items, 3 “I get a sort of frightened feeling as if something awful is about to happen” and 5 “worrying thoughts go through my mind” performed similarly to total depression and anxiety subscales in terms of their association with depressive and anxiety disorders respectively, at 12-months post-injury. Limitations: Patients were predominantly injured in motor vehicle accidents and received comprehensive care within a no-fault accident compensation system and so may not be representative of the wider TBI population. Conclusions: Although validation is required, a small number of self-report items are highly associated with 12-month post-injury diagnoses.