OBJECTIVES: Chronic myelogenous leukaemia (CML) is a progressive disease newly diagnosed in approximately 50 patients a year in Scotland. It is associated with significant health and economic burden. Dasatinib is a new treatment indicated for patients with CML who failed imatinib therapy. The purpose of this study was to estimate cost-effectiveness of dasatinib vs. imatinib in patients with chronic phase CML resistant to imatinib from the perspective of NHS Scotland. METHODS: A Markov model was developed to estimate the lifetime costs and health outcomes associated with dasatinib (140mg/day) compared to imatinib (800mg/day) in chronic phase CML patients resistant to imatinib therapy. Patients progress through the disease in monthly cycles based on their initial best response to treatment: no response, complete haematological response, partial or complete cytogenetic response, as observed in a randomised Phase II trial. The rate of progression was based upon estimates from published literature. Utility values used were obtained using the EQ-5D in a CML utility study based on patient's current health status and level of response. Resource use was estimated by expert haematologist and unit costs were taken from national databases. Costs and outcomes were discounted at 3.5% per annum. One-way and probabilistic sensitivity analyses were conducted to estimate the stability of the results. RESULTS: In chronic phase CML, treatment with dasatinib resulted in 0.68 incremental life years, 0.63 incremental QALYs, and savings of £10,579 over the patient's lifetime compared to treatment with imatinib. Treatment with the lower-cost dasatinib reduces overall costs due to fewer patients progressing to the advanced (and costly) stages of CML. The results were stable under a range of sensitivity analyses. CONCLUSION: Compared to imatinib, dasatinib is associated with increased effectiveness at a lower cost; dasatinib is a dominant treatment option for patients with chronic phase CML resistant to imatinib.