OBJECTIVES To analyse the cost-minimization of viscosupplmentation in comparison with arthroscopy/lavage for the treatment of moderate osteoarthritis of knee. METHODS A cost-minimization analysis from the Brazilian Private Payer perspective, with a time horizon of 2 years was conduct. A decision tree considering the probabilities of treatment fail or success, were performed. Study comparators examined were Hyaluronic Acid (Synvisc©) and Arthroscopy with Lavage (Arthroscopy). The clinical aspects regarding benefits and probabilities data were extracted from clinical trials and meta-analysis of clinical trials for the alternatives. The analysis was based on Brazilian current clinical practice. Treatment costs were collected from a private payer's database. Costs and benefits were validated by a panel of Brazilian specialists from payers. Due to short term analysis discounting was not applied, the results were converted in US Dollars (R$2.3/USD 1.00). A one-way sensitivity analysis was performed. RESULTS Patients using Hyaluronic Acid get the lowest total cost per treatment (Synvisc©= USD 2,042 OR R$4.697; Arthroscopy=USD 2136 OR R$4.913). The results were sensitive to Hyaluronic Acid cost regarding all other variables base case were robust in an interval of ± 20%. CONCLUSIONS Viscosupplementation is a cost-saving alternative for for the treatment of moderate osteoarthritis of knee compared to arthroscopy/lavage in the perspective of Brazilian's Private Sector.