A valid passport is required for U.S. citizens to enter Argentina. U.S. citizens do not need a visa for visits of up to 90 days for tourism and business. U.S. Passport must be valid 3 months beyond intended stay. Tickets and Documents for return or onward travel
On December 20, 2009, the Government of Argentina will begin charging American Citizens visiting Argentina for business or tourism an entry fee of $131 U.S. dollars. The fee will be collected only at Buenos Aires Ezeiza International Airport. Once paid, the fee permits multiple entries into Argentina for ten years in accordance with United States visa reciprocity. Americans may pay in dollars, by credit card, or with travelers checks
No Visa Required for Stay up to 3 Months. Extension Possible for Stay of Further 3 Months (max). Vaccinations - International Certificate of Vaccination required for Yellow Fever if Arriving from Infected Area within 5 days
http://www.embassyofargentina.us