OBJECTIVES: Maintenance therapy with rituximab has shown significant improvements in overall survival and progression-free survival (PFS) when compared with observation in patients with relapsed/refractory follicular lymphoma (van Oers et al, 2006). The primary objective of this analysis was to estimate the incremental cost-efectiveness ratio (ICER) of rituximab maintenance therapy versus observation alone, based on data from the EORTC 20981 study. METHODS: Rituximab maintenance therapy (375 mg/m2 every 3 months) was evaluated using a Markov model. All patients entered in the model following response to CHOP chemotherapy +/- rituximab as induction therapy. PFS and Overall Survival (OS) following rituximab maintenance were extrapolated from 2-year Kaplan-Meier curves from the study data using a parametric approach. Cox-Snell and deviance residuals were analysed. Quality-of-life utility values were derived from a study of 165 patients using the EQ-5D questionnaire. Direct annual medical costs including adverse events, drug acquisition, administration and preparation were estimated accordingly to a Delphi panel with Brazilian haematologists. Costs were reported in 2007 Brazilian Reais. Both costs and outcomes were discounted at 3.5% rate according to NICE/UK recommendation. In order to assess uncertainty, probabilistic sensitivity analyses were also performed. A lifetime horizon and a payer perspective in Brazil were adopted. RESULTS: Rituximab maintenance resulted in a gain of 1.79 QALYs (5.96 vs 4.17) at an incremental cost of R$ 57,595 The ICER of rituximab maintenance vs. observation alone is, therefore, estimated to be R$ 32,236 per QALY gained. The ICER of rituximab maintenance was sensitive to the duration of treatment benefit, discount rate and drug cost. CONCLUSION: In patients responding to induction therapy, rituximab maintenance therapy improves overall survival and progression-free survival compared with observation alone. Results suggest that maintenance therapy with rituximab is a cost-effective intervention for the management of patients with follicular lymphoma in the Brazilian Private Healthcare System.