To assess, from a Canadian perspective, the economic impact of arsenic trioxide (ATO) + all-trans retinoic acid (ATRA) for treating newly diagnosed acute promyelocytic leukaemia (APL), the cost-effectiveness of ATO + ATRA compared to ATRA + idarubicin (IDA) was assessed over a lifetime horizon using a time-dependent Markov model. The model considers four health states: complete remission, treatment failure or relapse, post-failure, and death. Markov cycle length was 1 month for the first 48 months and 1 year thereafter. Efficacy outcomes in terms of event-free survival and overall survival were taken from a head-to-head clinical trial. Costs were associated with drug and administration, adverse events (AEs), treatment of relapses, follow-up visits, and productivity losses. Utilities and disutilities associated with health states and AEs were derived from the literature. Compared to ATRA + IDA, ATRA + ATO is associated with incremental cost-effectiveness ratios (ICERs) of $CAD50,193/quality-adjusted life years (QALY) and $CAD50,338/QALY from a Canadian Ministry of Health (MoH) and societal perspectives, respectively. Results of the one-way sensitivity analysis show that ICER varied from $CAD23,045 to $CAD60,759/QALY (MoH perspective) and from $CAD23,120 to $CAD60,905/QALY (societal perspective). ATO in the first-line therapy for patients with APL can be considered a more cost-effective strategy than standard treatment from a Canadian perspective. Copyright © 2014 John Wiley & Sons, Ltd.