Objective: Information on the pregnancy rate after successive in-vitro fertilization (IVF) cycles and their associated costs is relevant for couples undergoing assisted reproduction treatments (ARTs). This study, therefore, sought to investigate the effectiveness and the costeffectiveness of two ARTs, the minimal ovarian stimulation IVF (MS-IVF) compared to the conventional ovarian stimulation IVF (C-IVF) from the payer's perspective.Methods: A 10-months follow-up prospective observational study was conducted in a sample of couples who sought ARTs in a private clinic in Southern Brazil. Women had to satisfy the Bologna Criteria and be older than 35 years. The effect outcome was pregnancy rate per initiated cycle. Medication costs were based on medical records. Costs and effect differences were estimated using seemingly unrelated regressions adjusted for the propensity score estimated based on women's characteristics.Results: All 84 eligible women who agreed to participate received a total of 92 IVF cycles (MS-IVF, n=27[35 cycles]; C-IVF n=57[57 cycles]. The effect difference between MS-IVF and C-IVF was -5.1% (95%CI, -13.2 to 5.2). Medication costs of MS-IVF were significantly lower than C-IVF by €-1260 (95%CI, -1401 to -1118). The probabilities of MS-IVF being cost-effective compared to C-IVF ranged from 1 to 0.76 for willingness-to-pay of €0 to €15,000 per established pregnancy, respectively.Conclusions: Even though there were no positive effect differences between groups, MS-IVF might be costeffective compared to C-IVF from the payer's perspective due to its relatively large cost savings compared to C-IVF. However, further investigation is needed to confirm these findings in a larger sample.