The hospital anxiety and depression scale (HADS) is a widely used and popular self-report measure that has been extensively translated and utilized in a broad variety of clinical populations. This 14-item measure has been subject to two previous reviews exploring a number of psychometric aspects of this tool. A relatively consistent finding of previous reviews of this instrument is that it is a reliable and valid measure of two independent and separable dimensions of anxiety and depression; indeed, this aspect of the HADS is crucial to the validity of the measure in clinical practice. The current review examines contemporary research reports that use factor analytic techniques, which suggest that the assumed bi-dimensionality of the HADS is, in fact, erroneous. The findings from the current review suggest that the HADS is underpinned by a tridimensional factor structure comprising dimensions of anhedonia, negative affectivity and autonomic arousal. Implications for the use of the HADS in light of these observations are discussed and recommendations made within the context of screening practice for the referral to liaison psychiatry services.