BACKGROUND: Toxic epidermal necrolysis (TEN) is a rare but fatal condition characterised by cutaneous exfoliation of the dermoepidermal layer and mucosal surfaces. Extensive TEN with epidermal detachment >30% of the total body surface area has been associated with a high mortality. OBJECTIVE: This study aims to evaluate factors associated with mortality in extensive TEN. In the absence of data to qualify scoring systems such as SCORTEN, this study also aims to evaluate the use of the auxiliary score as a tool for calculating expected mortality. METHODS: A retrospective chart review of all patients presenting to our burns service with extensive TEN was undertaken. Application and evaluation of the auxiliary score was also undertaken for this patient population. RESULTS: In extensive TEN, age and delay in admission to a burns centre were factors associated with mortality. Applying the auxiliary score to our patient population, there were no significant differences between expected mortality and observed mortality. CONCLUSION: Mortality was associated with age and delay in definitive treatment in extensive TEN. Whilst SCORTEN is the gold standard prognostic tool for patients with TEN, in the absence of SCORTEN values, the auxiliary score provides an alternative scoring system to evaluate expected mortality.