Objectives: To explore whether a semi–structured post-traumatic amnesia (PTA) assessment interview (PTA-I) provides a practicable but equivalent estimation of PTA in patients attending the Emergency Department (ED) with head injury (HI) compared to the established Westmead PTA Scale Revised (R-WPTAS). Procedure: PTA was assessed using the R-WPTAS (includes a visual memory component) and the PTA-I (includes retrospective and verbal memory components), in patients attending an ED with (n=30) or without (n= 30) HI. Outcome measures were the Post-concussion Syndrome Checklist (PCSC) and the Glasgow Coma Scale (GCS). McNemar’s Tests and Chi-square analyses were used to determine the results. Results: The verbal memory component overestimated PTA in the control group by 24 %. Overall, the PTA-I did not discriminate between HI and control participants. However the retrospective PTA assessment embedded within the PTA-I did, with 100 % accuracy. Conclusions: The use of a verbal memory component to assess PTA in the ED is not supported by the results of this study. A retrospective PTA assessment appears to allow more accurate decision making regarding the admission criteria used in the ED and has advantages over the R-WPTAS: fewer test materials and no repeat assessments required to achieve an estimate of PTA duration.