You can use a checking bankcard, credit card or debit card, and will find ATM's at every bank, in or near many supermarkets, in shopping malls, grocery stores and occasionally in hotel lobbies. ATMs are linked to Cirrus, Plus and other major International networks, and are available 24 hours a day.

Call Bank and Credit Card Companies prior to trip to inform them of the locations where the card may be used to prevent it from being deacctivated.

For safety, you should stick to ATMs in or attached to bank branches.  There have been instances of phony ATMs or ATM facades put up in non-bank locations to harvest card numbers and personal ID codes (this applies to the U.S. too!).

In addition to being convenient for quick withdrawals, bank ATMs carry out their transaction at the wholesale banking rate. This means you will typically get a better exchange rate by using an ATM than you would with cash or travelers' checks at a bank.   Banamex is owned by Citigroup (Citibank). Most ATMs found anywhere are in English and Spanish, but the money amount will always be shown in Mexican pesos. If you want $200 U.S. in pesos, you need to type in 2500, otherwise if you type in 200, you get roughly 15 dollars in pesos (at a rate of 13 to 1). In Northern Mexico and some tourist areas, some ATMs also offer U.S. dollars; Banorte and HSBC are two banks with this option at many of their ATMs.

The amount you are allowed to withdraw is the amount your bank allows you per day. The withdrawal fee is whatever fee your bank charges for international or out of network usage. Many banks in Mexico may not charge a fee for ATM usage.  For those that do, it commonly ranges from $1 to 1% of the amount withdrawn; this is less than the "markup" on the exchange rate for exchanging dollars for pesos at a bank or currency exchange. The ATM may not tell you the fee during the transaction as occurs in using ATMs in the U.S. and elsewhere; it is deducted in the transaction by being added to the amount charged to your account rather than charged separately to your account. In the transaction detail it will be called an ISF charge.  NOTE: Many USA banks charge a fee if you use a foreign ATM - some that don't (or charge $1) include Schwab, Fidelity, Paypal.  Bank of America and Wells Fargo charge a $5 to use non-BofA and non-Wells ATMs.  

Most ATMs will also accept your Visa or MasterCard (if you have a PIN number, and can withdraw money from the credit card) for a cash advance. If you do not know your PIN for your credit card you cannot get it while you are in Mexico! Credit card companies will only send you the PIN number via the mail or if you are calling from your home telephone number or the phone number registered with the credit card company. So remember no PIN number = no money!   It is good to know that most ATMs in Mexico (and most of the world) only accept four (4) digit PINs, this includes debit cards and credit cards. If you do not have a four digit PIN number, it is advisable to speak with your bank before traveling.

Even if you don't plan on using a credit card, it's a good idea to bring one along to have in case of emergency, or a great shopping spree, and it is safer than carrying around large amounts of cash.

Another reason to keep an eye on your credit card is cloning. Credit card cloning has become an epidemic world wide, and can wreck a vacation. Make sure if you use your credit card, anywhere, you have your eye on it the entire time, or pay the cashier directly yourself. It is not the carbon sheets or the receipts that are of issue, it is the actual card and a cloning machine.

When you use any credit card internationally you are charged at least a one percent fee by the Visa/MasterCard clearinghouse, no matter what country you are in and which bank's card you use. Most people are unaware of this fee. It is imposed at the currency exchange level as part of the transaction. But in addition to the clearinghouse fee, some issuers have begun to charge an additional two to five percent fee for international credit card transactions.  Check with your bank to find out it's fees.  At this time (Nov 2007) UBS and Capital One are the only known banks that don't even charge 1% (some Chase cards are also free of forex fees). 

American Express charges a two percent fee for international transactions with its card. Before you rely on plastic as your major means of money while on vacation, check with your credit card company about their international policies. In the end, you may be paying 10% more than if you would have paid with cash.