provided by Entry and Customs in Greece
Traveling to Greece require certain entry formalities to be cleared.
Citizens of the United States, Canada, Australia, New Zealand and other non European Union needs a valid passport with the date of entry and exit stamped on it.
While people from European Union do not require this and can stay for unlimited period in Greece.
Custom in Greece is very strict to drugs.
The citizens from US and other non European nations have certain limits on carrying goods to Greece. Although European Union is free from all this limits.
Basically, one could carry things of personal use in Greece but not any things for trading purpose.