OBJECTIVES: This economic evaluation assesses the cost-effectiveness of rituximab added as maintenance therapy once every three months for two years after induction chemotherapy for patients with relapsed/refractory follicular lymphoma in Sweden, primarily based on data from the EORTC20981 trial. METHODS: The economic model evaluates the incremental cost and effectiveness of rituximab maintenance therapy versus observation alone. A hypothetic patient cohort, aged 55 years at the start of simulation, was followed in a state-transition Markov model in monthly cycles over a period of 30 years. Primary clinical endpoints were quality-adjusted life-years (QALYs) and life-years gained (LYG). Progression-free and overall survival data from the EORTC20981 trial were used to calculate model state transitions. The analysis was made from the perspective of the healthcare provider, including direct medical costs presented in €2006 value. Effects and costs were discounted at a 3% annual rate. One-way sensitivity analyses were performed to test the stability of the results and identify input parameters with particular influence on the results. A probabilistic sensitivity analysis was performed to test the joint instability of the model parameters. RESULTS: The calculations showed that rituximab maintenance therapy was associated with an incremental cost per QALY gained of €12,600 and an incremental cost per LYG of €11,200. The average discounted life expectancy in the rituximab group was 1.0 years longer than with observation (5.96 versus 4.94). Rituximab maintenance was associated with an additional 0.89 QALYs and total costs per patient were €11,500 higher in the treatment arm, compared to observation. The cost difference was mainly attributable to cost and administration of the study drug. Sensitivity analyses showed that the results were stable. CONCLUSION: The results indicate that maintenance treatment with rituximab after induction therapy for patients with relapsed/refractory follicular lymphoma in Sweden is cost-effective as compared to observation alone.