Local currency is US$. Since September 2008 we don't accept US$ traveller checks anymore. You can exchange them personally in the exchange office Vaz Corp. (Av. Amazonas N21-147 y Roca).
At some cash points you can take out up to US$ 800. The EC-credit card (Maestro) is more convenient than it is for example Visa. Many travel agencies do not accept credit cards and if they do, they normally add to the bill 15 % taxes. Credit cards can be very useful for buying flight tickets directly from an airline office or in case of an emergency (for paying hospitals, etc.).