OBJECTIVES: To evaluate the cost-effectiveness of bendamustine compared with chlorambucil as first-line treatment for patients with chronic lymphocytic leukemia who would be considered unsuitable for treatment with fludarabine combination chemotherapy regimens. METHODS: A semi-Markov approach was used to estimate time in each health state. The model was parameterized primarily by using data from a phase III randomized, open-label trial comparing bendamustine with chlorambucil. It captured the increased progression-free survival and improved response rates with bendamustine, and the cost and quality of life impacts of postprogression treatments. The analysis was conducted from the perspective of the National Health Service in England and Wales. A lifetime (35-year) time horizon was used. Deterministic sensitivity analyses, probabilistic sensitivity analyses, and subgroup analyses in older patients and patients with poor performance status were carried out. RESULTS: The estimated incremental cost-effectiveness ratio was £ 11,960 per quality-adjusted life-year. None of the deterministic sensitivity analyses increased the incremental cost-effectiveness ratio by more than £ 2000. Subgroup analyses showed that bendamustine remained cost-effective across different patient groups. Probabilistic sensitivity analysis showed that at the £ 20,000 threshold, bendamustine has a 90% probability of being cost-effective. CONCLUSIONS: Bendamustine represents good value for first-line treatment of patients with chronic lymphocytic leukemia who are unsuitable for treatment with fludarabine combination chemotherapy. The incremental cost-effectiveness ratio is below the thresholds commonly applied in England and Wales (£ 20,000-£ 30,000 per quality-adjusted life-year).