OBJECTIVES: Unintended pregnancy promotes a negative social impact worldwide and it represents a significant economic burden to the health system. According to a Brazilian study the total medical costs of an UP for SUS was estimated at BRL4.1 billion annually. Adolescent women have a high risk of UP and complications during pregnancy and child-birth are considered the second biggest cause of mortality of 15 to 19 year-old adolescents. SARC methods require active user compliance for pregnancy prevention, whereas long-acting reversible contraceptive methods don’t rely on user adherence for effectiveness. Therefore this study aims to evaluate the cost-effectiveness of LNG-IUS compared to oral and injectable contraceptives in avoiding UP in adolescents under the perspective of SUS. METHODS: To evaluate the efficacy of each method, the main endpoints adopted were failure and discontinuation rates based on The Contraceptive CHOICE project. A Markov model was developed to follow the adolescents along the natural course of contraceptives use, under a time horizon of five years. The costs adopted for the economical analysis were BRL2293,00 for an UP, the maximum government selling price for LNG-IUS and prices obtained from public disclosures available in the Official Gazette for oral and injectable contraceptives. Univariate and probabilistic sensitivity analysis were performed to evaluate the results. Costs expressed in 2016 prices and exchange rate was 1.00USD=3.70BRL. RESULTS: LNG-IUS has the lowest failure and discontinuation rates when compared to SARC hormonal methods in adolescents. The cost-effectiveness results showed that LNG-IUS is able to bring savings with gain in effectiveness when compared to oral and injectable contraceptives, revealing itself as a dominant method. Sensitivity analyses confirmed the results found in the base case. CONCLUSIONS: Considering the clinical and economic satisfactory results, LNG-IUS represents a cost-saving method that should be considered as an important alternative to avoid UP in 15 to 19 year-old adolescents.