Primary objective: To investigate the clinical potential of the Depression, Anxiety and Stress Scales (DASS 42) and its shorter version (DASS 21) for assessing emotional status following acquired brain injury. Methods and procedures: Participants included 23 individuals with traumatic brain injury (TBI), 25 individuals with brain tumour and 29 non-clinical controls. Investigations of internal consistency, test-re-test reliability, theory-consistent differences, sensitivity to change and concurrent validity were conducted. Main outcomes and results: Internal consistency of the DASS was generally acceptable (r > 0.70), with the exception of the anxiety scale for the TBI sample. Test-re-test reliability (1-3 weeks) was sound for the depression scale (r > 0.75) and significant but comparatively lower for other scales (r = 0.60-0.73, p < 0.01). Theory-consistent differences were only evident between the brain tumour sample and non-clinical control sample on the anxiety scale (p < 0.01). Sensitivity to change of the DASS in the context of hospital discharge was demonstrated for depression and stress (p < 0.01), but not for anxiety (p > 0.05). Concurrent validity with the Hospital Anxiety and Depression Scale was significant for all scales of the DASS (p < 0.05). Conclusions: While the results generally support the clinical application of the DASS following ABI, further research examining the factor structure of existing and modified versions of the DASS is recommended.