Riels and U.S. Dollars are both used in Cambodia.
Prices are both in United States Dollars and Riels. You can pay either in U.S. Dollars or Riels or a mix of U.S. Dollars and Riels.
If you pay in U.S. dollars you may be given change back in either U.S. Dollars (for the part greater than $1) and Riels (for the part less than $1). E.g. If you give a $5 bill to buy an item that cost $1.5 you will be given back $3 and the remaining in Riels.
2 exchange rates are used within a same transaction:
– 1 USD = 4200 Riels
– 1 USD = 4000 Riels

* The rate applied is always to the benefit of the seller (as a tourist you are often the buyer).
* An item costs $1. You can pay it in dollars or with 4200 riels (1 USD = 4200 Riels).
* An item costs $1.5. You give $2, the seller will give you back 2000 riels (1 USD = 4000 Riels).
* An item costs 5000 Riels. If you pay in USD you will pay $1 + 1000 Riels (1 USD = 4000 Riels)

Inflation has been quite steep in Cambodia, so check out the Riel/Dollar exchange rate before you go.

Banks have become somewhat obsolete in many places due to the advent of ATM’s, in Cambodia they are quite useful.  You can cash U.S. dollar checks at most banks and money exchange places for a 2% charge, and get your money in U.S. dollars.  This is no more expensive than using an ATM, once you figure in bank fees.  Note that this is most useful if you can buy your checks without a commission, which some banks and other organizations (the AAA in the U.S., for example) offer their customers. You can visit to get more information about this.