OBJECTIVES: To estimate the cost-effectiveness of the original r-hFSH (Gonal-f) when compared with one biosimilar (Bemfola) using the evidence from a head-to-head registration trial. METHODS: An Excel-based decision-tree model was developed depicting the different relevant outcomes that result from fertility treatment with r-hFSH. Probabilities were populated using the data from a head-to-head trial used by the biosimilar for its registration at EMA, using as relevant outcome the take-away baby rates found in the trial. Costs were populated from Portuguese official sources and include the cost of the two drugs, as well as the costs related with treatment, such as costs for IVF, ICSI, child delivery and abortion. The analysis was performed from a societal perspective including only direct medical costs with no discounting since all costs occur in a single year. RESULTS: According to the model, treatment of 1.000 women with Gonal-f will result in a total number of 447 pregnancies, with 407 women achieving a new-born child. Total cost for this will be 3.062.802,80 €, for a cost per woman achieving a new-born child of  7.534,49 €. Respective values for the biossimilar are 361 pregnancies and 321 women with new-born children. Total cost for this alternative is 2.957.530,12 €, resulting in a cost per new-born child of  9.205,31 €. Incremental cost-effectiveness ratio obtained for Gonal-f vs Bemfola is 1.235,32 € per woman with a new-born child. Sensitivity analysis did not change the hierarchy in the results except on extreme values. For cost-effectiveness ratios to be similar the biosimilar would need a 91% price reduction. CONCLUSIONS: The biossimilar is extendedly dominated by Gonal-f, with its cost-effectiveness ratio being higher than the one found for Gonal-f. Under the current scenario the use of the biossimilar is not a cost-effective alternative to the use of Gonal-f and thus should be avoided.