OBJECTIVES:  An unplanned pregnancy can have profound consequences, e.g., unsafe abortion, which is a public health problem in Brazil. Ensure access to highly efficient contraceptive may impact in reducing unplanned pregnancies. Therefore, this analysis aimed to evaluate the cost-effectiveness of long acting reversible contraceptives (etonogestrel implant versus levonorgestrel intrauterine system), from the Brazilian private health perspective. METHODS: The eligible population was private insurance beneficiaries in September 2016 that were current users of levonorgestrel intrauterine system, aged 19 to 48 years. Efficacy, cost and market-share of contraceptives data were obtained from local sources. Annual discontinuation and failure rates of each method were considered. Average cost of an unplanned pregnancy was 3,181.33 BRL. The prices for etonogestrel implant and levonorgestrel intrauterine system were 902.85 BRL and 760.33 BRL, in addition to 173.5 BRL and 236.52 BRL, respectively, as reimbursement by procedure. For levonorgestrel intrauterine system, it was also considered a hysteroscopy in 25% of cases in the base case and 75% in the alternative scenario. Time horizon was 15 years, with yearly cycles. Costs and benefits were discounted by 5% per year. RESULTS: In an initial population of 213,714 women, etonogestrel implant avoided 395 unplanned pregnancies after 15 years, with savings in device costs and unplanned pregnancies costs, therefore being cost-saving, in both scenarios. The reduction in total costs was of 27.117.307 BRL for the base case and 159.161.722 BRL for the alternative scenario. CONCLUSIONS: Compared to levonorgestrel intrauterine system, etonogestrel implant was cost-saving, with a reduction of unplanned pregnancies and costs. Given its high efficacy and cost-effectiveness, etonogestrel implant should be included as an option for women in the private health sector of Brazil.