How safe it is to use a CC in Argentina and Chile ? Do they normally take US dollars cash ?

As with almost any country in the world, it depends on where and how you use it. Big cities in both Argentina and Chile are fine for using credit and debit cards. Many business accept dollars, but you will be better off using local currencies or your plastics.

Amex is the safest, but could be problematic on many places, as is the least common of the three big ones.

Right now, dollars are more valuable in Argentina, as there is a nationwide currency change control. The usual rate is 1USD=4,80 ARS, but in many places you will get something more like 1USD=6 ARS.

Chile doesn't have the dollar issues of Argentina. In Chile dollars cash would not be common in anything but a hotel or tourist service. Everything else is pesos or credit card. Everyone uses credit or debit cards in Chile for just about everything, although remote areas will be short of ATM machines. Easter Island is awkward for credit card use as it takes an age for businesses to be reimbursed and there are few ATM machines. Visa and Mastercard are the most common cards. American Express is less used. If you can bring two different cards it helps. We use a four digit pin.

We used USD in Argentina more frequently last month than on other trips the past few years. You still need pesos for taxis, smaller shops, etc.

Credit cards are not used as frequently in the smaller towns due to the higher fees the restaurants and shops pay. We saw many signs in El Calafate stating cc were no longer accepted.

So, it just depends on your destination within Argentina as to what method of payment you should use.

Thanks for your replies. I'll be moving from Argetina to Chili in the very south, so probably I won't have a chance to exchange back unused pesos.

You can still change Argentine pesos for Chilean ones in Chile. You don't get a great rate but you get something.

We never found ATM's working in Calafate. The one in Chalten sometimes has money, sometimes not....I would make sure to have pesos (and dollars) before I arrive in either town if you are visiting there.

Calafate was the only town where the exchange on dollars was below the official rate, so we used pesos and/or credit cards, when accepted.

I believe, based on the line of people waiting, that there was at least one working ATM in El Calafate on my recent visit. But I agree that you should take all the money you will need in case there is none working. And so you don't have to stand in line.

I just got back from Chile and found that many banks charge very high ATM fees there. $6-$8 is typical, especially in airports, but also all the ATMs in San Pedro de Atacama. By hunting around and trying many banks in Santiago and in Puntarenas we were finally able to find no fee ATMs. They don't tell you about the fee and tell you've already put in your card and PIN, and selected amount to withdraw, but you can cancel the transaction with no fee.

Another reason I have a Capital One current account and ATM card. In the two months I just spent in SA I don't think I used one ATM that didn't charge a fee. Capital One "eats" up to $25 a month in fees.

Both Chile and Argentina have a fee for transactions with a foreign credit card on ATMs. Banco Estado and Banco Security don't, depending on the system your cc uses.