Passports and visas
Greece is both a member of the European Union (EU) and the European Economic Area (EEA). All EU nationals (including citizens of new member states) may enter Greece with a valid national ID card; this includes non-member states affiliated with the European Union, such as Monaco and Andorra. Citizens from EEA states that are not members of the EU (such as Switzerland, Norway, and Iceland), may also enter Greece with a valid national ID card.
A valid passport is required of all non-EU and non-EEA nationals, and most are also required to obtain a visa. Citizens of certain countries, including Argentina, Australia, Canada, Chile, Croatia, Hong Kong SAR, Israel, Japan, South Korea, Malaysia, Mexico, New Zealand, and the United States, are allowed a 90-day visa-free stay. Citizens of Brazil and Uruguay are allowed a 60-day visa-free stay. For the most recent information on entry requirements, contact your nearest Greek consulate.
Greece is a signatory of the Schengen agreement along with Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Italy, Iceland, Luxembourg, the Netherlands, Norway, Portugal, Spain, and Sweden. There are no passport checks when traveling between any two Schengen countries. A non-Schengen national who plans on visiting multiple Schengen countries -and who needs a tourist visa to visit them- may do so on just one visa from one Schengen country; but he is advised to specifically obtain the visa for the first country he will be visiting.
For detailed regulations applied to your country, refer to Greek Ministry for Foreign Affairs (http://www.mfa.gr/en/)
Source
http://wikitravel.org/en/Greece