OBJECTIVES:  Mucormycosis is a rapidly progressive fungal infection, associated with high mortality, particularly when appropriate treatment is not promptly initiated. Until recently, the only licensed treatments were amphotericin B (AMB) formulations, which have considerable limitations. AMB deoxycholate is nephrotoxic, while the less nephrotoxic liposomal AMB (L-AMB) – standard treatment in the United Kingdom (UK) – is costly. Isavuconazole (ISAV) is a new intravenous and oral triazole antifungal for the treatment of mucormycosis in adults for whom AMB is inappropriate. A cost-minimisation model was developed to explore the cost of treating mucormycosis with ISAV versus L-AMB followed by maintenance treatment with off-label, oral posaconazole (POSA) in the UK. METHODS:  The cost-minimisation analysis estimated per-patient treatment costs for mucormycosis from the UK National Health Service perspective. The time horizon was until end of treatment. A matched case-control analysis of the phase III, single-arm VITAL study of ISAV in mucormycosis and the FungiScope™ registry showed similar efficacy of ISAV and AMB (mainly L-AMB) ± POSA. Treatment-related costs comprised on-treatment drug acquisition, monitoring and administration costs, and hospitalisation costs. Clinical inputs, including treatment durations and dosing regimens, were derived from the VITAL study and FungiScope™ analysis. Monitoring requirements were based on adverse events and precautions reported in Summary of Product Characteristics documentation. Unit costs were from publicly available UK sources. RESULTS:  The estimated per-patient cost of treating mucormycosis with ISAV and L-AMB + POSA was £26,810 and £41,855, respectively. Savings were primarily driven by reduced drug acquisition costs with ISAV relative to L-AMB + POSA, alongside lower hospitalisation costs since ISAV patients could be switched from IV to oral treatment earlier than LAMB + POSA patients. CONCLUSIONS:  Based on the matched case-control comparison between patients receiving treatment with ISAV or L-AMB, ISAV is expected to reduce costs by 36% compared with standard mucormycosis treatment in the UK.