I recall a previous post that some people had problems with their credit cards being accepted on Trenitalia's web site, especially AX. I just attempted to use my AX card and it was refused. I was successful using my visa (but lost the mini fair in the process). American Express sent me a fraud alert email so now I'm hold with AX to let them know this was a valid charge attempt. So advice to people using a credit card, but especially American Express, is to call AX in advance and alert them to a transaction on Trenitalia web site.
Karen, American Express isn't as widely accepted in Europe, partially due to the higher fees they charge merchants. Probably best to use Visa or MasterCard for most travel-related transactions.
I wouldn't bother taking an AMEX card with me to Italy. Most places won't take them so just bring a Visa or Mastercard. Trenitalia has been notorious for not taking AMEX and has just recently started taking North American issued credit cards. Donna
For the most part mostly large hotels, fancy restaurants and high end shops take Amex in Europe. Trenitalia only takes Italian Amex last time I checked. I mostly used my Capital One Visa card in Italy last month but I used my Amex twice and was charged an international transaction fee from Amex which I though they no longer charged.
I wasn't planning on taking AX card to Italy with me and will mostly rely on our zero fee ATM cards. Was at home booking train reservations. It wasn't Tenitalia that did not take the card, it was AX declining the transaction as they thought it may be a fraudulent transaction. So for those planning their trip and paying deposits or other travel related European expenditures while still in the US, probably not a bad idea to alert your credit card company to expect transactions.