Overall, credit cards (mainly MasterCard and Visa) are accepted in most places in Greece, but you should first make sure yours are valid abroad.    So first thing before your trip, notify your card company that you will be using the card abroad. However, that said, I wouldn't suggest using credit cards because some companies charge an extreme conversion fee from dollars to euros.    Make sure to ask your credit card issuer if there is a foreign transaction fee with use abroad and instead use a card that waives this.    Do not use your credit card at an ATM to get cash and not a good idea to use your debit card to buy things abroad (3% on transaction).   If you clarify with your company what the extra charges will be for use of card abroad then it's ok. I suggest you always have some cash with you because if you travel to smaller off-the-beaten track places or small islands, they most likely will not accept cards.    Also check to see if your card offers travel-related rewards likes points for flights and hotel stays. Another idea would be using a pre-paid travel card.   One more thing, you're more likely to get a better price at shops if you pay in cash.