MasterCard and VisaCard are accepted in most of the establishments, as long as it's not drawn on an American bank. Unfortunately, it's part of the US embargo restrictions on Cuba. No US travelers cheques either.

You can extract cash of cards in several banks and big hotels in all the Island, but is advisable to bring money in cash since the extraction can take time and in many places you only can pay in cash. Also you can use traveler's checks for the payment of some services.