OBJECTIVES: Imatinib combined with conventional chemotherapy (CC) in Ph+ALL patients has produced encouraging efficacy results with a well-tolerated safety profile. This study explores the cost effectiveness of imatinib plus CC versus CC alone in adult Ph+ALL patients. METHODS: A Markov model simulated a hypothetical cohort of adult Ph+ALL patients receiving imatinib plus CC or CC alone. The model included three states: alive without disease progression (DFS), alive with disease progression (DS), and death. State transition probabilities were derived from the published literature. In the absence of relevant data pertaining to Ph+ALL, assumptions about costs and utilities were derived from a cost analysis of CML. Only direct medical costs were included, adopting a UK healthcare payer perspective. All outcomes were discounted. An adaptation of the model to the US perspective was conducted as well. RESULTS: The model projects that the total discounted survival was 1.10 years for CC and 4.31 years for imatinib+CC. Total discounted disease free survival was 0.76 year for CC and 2.77 years for imatinib+CC. The total discounted quality adjusted life years (QALY) were 0.85 v. 3.28 for CC and imatinib+CC, respectively. Thus, the net incremental gain in discounted quality adjusted survival was 2.43 QALYs. The monthly costs of DFS and DS were estimated at £123 and £417, respectively. The net costs associated with imatinib were £51,757 for the UK. The incremental cost per QALY of imatinib+CC v. CC alone was approximately £21,290 (i.e., £51,757 divided by 2.43 QALYs). Adapting the model to the US perspective, the incremental cost per QALY was about $42,000. CONCLUSIONS: For adult ALL patients with poor prognosis due to Ph+ALL, our exploratory analysis suggests that, given the underlying data and assumptions, adding imatinib to current chemotherapy regimens is cost-effective compared to chemotherapy alone both from the UK and the US perspectives.