ObjectiveTo determine the cost-effectiveness and cost-utility of a quadpill containing irbesartan 37.5 mg, amlodipine 1.25 mg, indapamide 0.625 mg and bisoprolol 2.5 mg in comparison with irbesartan 150 mg for people with hypertension who are either untreated or receiving monotherapy.MethodsWe conducted a within-trial and modelled economic evaluation of the Quadruple UltrA-low-dose tReaTment for hypErTension trial. The analysis was preplanned, and medications and health service use captured during the trial. The main outcomes were incremental cost-effectiveness ratios (ICERs) for cost per mm Hg systolic blood pressure (BP) reduction at 3 months, and modelled cost per quality-adjusted life year (QALY) over a lifetime.ResultsThe within-trial analysis showed no clear difference in cost per mm Hg BP lowering between randomised treatments at 3 months ($A10 (95% uncertainty interval (UI) $A −18 to $A37) per mm Hg per person) for quadpill versus monotherapy. The modelled cost-utility over a lifetime projected a mean incremental cost of $A265 (95% UI $A166 to $A357) and a mean 0.02 QALYs gained (95% UI 0.01 to 0.03) per person with quadpill therapy compared with monotherapy. Quadpill therapy was cost-effective in the base case (ICER of $A14 006 per QALY), and the result was sensitive to the quadpill cost in one-way sensitivity analysis.Conclusion(s)Quadpill in comparison with monotherapy is comparably cost-effective for short-term BP lowering. In the long-term, quadpill therapy is likely to be cost-effective.Trial registration numberANZCTRN12616001144404.