The official Vietnam Currency is Vietnam Dong (VND). In 2010-11, the approximate exchange rate of Vietnam Dong to US Dollars is about VND20,000 to US$1. Thanks to its low value compared to other major currency, travelling to Vietnam is kept at a very affordable rate. It might take some time to orient yourself around the number of 0s that you might never have seen before.
Credit cards and debit cards are not yet popular in Vietnam and do not expect those cards to be accepted in grocery stores and pharmacies. That leaves cash as the main exchange medium on a daily basis. There is no coin in operation nor any vending machines operated with coins. Vietnam Dong bank note has seen much change since its first appearance in 1945. The latest version of Vietnam Dong varies in both colours and the denominations. The larger notes are made of polymer material and the smaller ones are from cotton.