OBJECTIVES: To evaluate the long-term cost-effectiveness of a fixed-dose combination (FDC) therapy (0.5mg dutasteride and 0.4mg tamsulosin daily) compared to 0.4mg tamsulosin monotherapy for the treatment of symptomatic benign prostatic hyperplasia (BPH). METHODS: We developed a Markov state transition model with tunnel state and embedded decision tree. The model follows a Quebec cohort of 312,448 male patients aged ≥50 years, diagnosed with BPH and with symptoms as defined by an International Prostate Symptom Score ≥12. This cohort reflects the population of the 4-year ComBAT trial to evaluate the effect of combination therapy versus either dutasteride or tamsulosin monotherapy on BPH clinical progression and improvement in BPH symptoms. We conduct this analysis from the perspective of the Quebec provincial healthcare system, considering all primary care and hospital costs. Utility estimates were obtained from published literature. Results are presented at 10 years and lifetime (up to 25 years) in the form of incremental costs, incremental QALYs and the incremental cost-effectiveness ratio (ICER). Sensitivity analyses were performed to evaluate the robustness of the model to variations in the underlying input parameters. RESULTS: Discounted QALYs per patient at a 10-year time horizon were 6.88 (FDC) and 6.82 (Tamsulosin).  At 10 years the ICER for FDC compared with Tamsulosin was CAD $29,860. The ICER decreased over time to reach CAD $29,239 over a lifetime horizon. At a willingness to pay of CAD $50,000 per QALY gained, the probability of FDC being cost-effective for the symptomatic BPH population was approximately 63%. CONCLUSIONS: FDC can be cost-effective in treating patients affected with enlarged prostate with moderate or severe symptoms. The sensitivity analyses suggested that variation in main parameters will not alter the behavior of the comparison between the two treatments (i.e. FDC is always more effective and more costly than tamsulosin at a lifetime time horizon).