US dollars are fine. We were just there in December and had no issues. It was our 10th trip to Mexico and we have always used US.

Most places are still accepting US dollars, but, it may cost you 15-20% to use them. Vendors often use a 10:1 exchange rate, when actually, the exchange is closer to 12:1.

I've also read that you can no longer spend more than US$100.00 per person for any tour or activity.

The Mexican government is really trying to make it difficult to launder drug money so easily.

And, you are a guest in a different country. Be courteous and use their currency.

Agreeing with the above. Yes it is common for businesses to accept USD in the Cancun area and on that side of Mexico (less so the rest of the country) but typically you'll get a 10/1 exchange. If you exchanged your own money or better yet use an ATM then you'll get closer to the 12/1. So basically you are paying a little surcharge each transaction by using USD if prices are in peso.

Smaller markets may not accept U.S. at all as the rules have changed and they are not taking foreign currency as a result of that. If they do exchange it (for instance WalMart and the ferry to Cozumel) sometimes the rate is even better than at the bank. Go figure. Two weeks ago the exchange was 11:1. Since the stores or anyone else who turns in money to the bank have had a limit on how much U.S. they can turn in, many of of them are not accepting foreign currency.

We were in Cancun just over a week ago and things had changed since our last visit regarding foreign currency.

Many places had signs indicating that they would no longer accept US$ including our hotels (Marriotts) and that it was now illegal.

We mostly used credit cards for larger purchases (one with no foreign transaction fees). We acquired some pesos in change to use at markets but we really didn't need a lot of cash as we bought very little on this trip (most things were prepaid).

Rate was generally 12:1