OBJECTIVES: Obinutuzumab is the first, glycoengineered type II antibody demonstrating increased Antibody-Dependent Cell-Mediated Cytotoxicity (ADCC) and direct cell death compared with rituximab, and is pending regulatory approval (in combination with chlorambucil (Clb)) for the treatment of patients with previously untreated chronic lymphocytic leukemia (CLL). Obinutuzumab+Clb has shown a > 85% reduction in the risk of progression, relapse or death in comparison to treatment with Clb alone (HR 0.14, 95% CI 0.09-0.21, p <.0001), a broadly accepted treatment option for many patients with co-existing medical conditions. The cost-effectiveness of this innovative therapy will need to be assessed in countries using incremental cost-effectiveness thresholds to make reimbursement decisions. METHODS: A four-state Markov lifetime model from the UK NHS perspective was developed for patients with existing medical conditions utilizing the patient-level information from the underlying clinical trial comparing obinutuzumab+Clb versus rituximab+Clb and versus Clb alone (CLL11 trial). Transition probabilities from PFS to progression were derived from this study’s data. Post-progression survival was estimated using published data and was part of the sensitivity analyses. Cost data (e.g. administration and adverse events), utilities and the prices for rituximab and Clb were retrieved for the UK. As obinutuzumab is not yet approved a range of price assumptions of similar innovative oncology therapies has been applied. RESULTS: Based on this early evaluation, obinutuzumab+Clb showed a cost per QALY in the base case analysis of £18,000 to £19,000 when compared to Clb and £29,000 to £32,000 when compared to rituximab+Clb. Probabilistic and deterministic sensitivity analyses confirmed these findings. CONCLUSIONS: Obinutuzumab+Clb showed significant patient-relevant clinical benefits and might be a potential cost-effective therapy in comparison to the current standard of care and could hence support access for a maximum number of patients with previously untreated CLL.