OBJECTIVES To determine the budget impact of incorporating levodopa/carbidopa/entacapone FDC in São Paulo's public reimbursement system for Parkinson disease treatment. METHODS In present analysis, it was considered the quantity reimbursed for São Paulo's state in 2007 in Parkinson Disease treatment, based on DATASUS (National public healthcare database). Results were converted in US Dollars (R$2.27/USD1.00). It was considered the medications costs used in São Paulo state's bidding: USD0.04/tablet for both combinations of levodopa/carbidopa; USD 0.51/tablet for both combinations of levodopa/benserazide; USD0.96/tablet for entacapone. Levodopa/benserazide's presentations have different prices, however to simplify the analysis, we took the price of the most used presentation (89% in units) and considered it for both. According to DATASUS, considering all levodopas' combinations reimbursed in São Paulo's state in 2007, 40% was levodopa/carbidopa and 60% was levodopa/benserazide. The price of all levodopa/carbidopa/entacapone FDC's were fixed in USD 0.97/tablet. A one-way sensitivity analysis was performed. RESULTS In São Paulo's state, the quantities reimbursed in 2007 for entacapone were 1,431,692 and for all levodopas' combinations were 8,765,930. Considering the prices used in São Paulo's bidding, the total of expenses was US$4,217,586. In this scenario, if levodopa/carbidopa/entacapone FDC is used in the place of free dosage combinations, then the total of expenses was estimated in US$ 3,771,147. The sensitivity analysis on cost variables in an interval of ±20% was robust with the base analysis. CONCLUSIONS This budget impact analysis showed a potential economy of US$446,438 if levodopa/carbidopa/entacapone FDC is incorporated in São Paulo's public reimbursement system. Besides, the use of FDC can provide higher adherence of patients to the treatment, once it is easier administrating one tablet instead of two or more; the patients prefer to take less quantity of tablets; the switches of dosage are easier.