Vietnam currency is Dong ( vnd).
Bank notes available: 100vnd, 200vnd, 500vnd ( rarely used, small value), 1000vnd, 2000vnd, 5000vnd, 10.000vnd, 20.000vnd, 50.000vnd, 100.000vnd, 500.000vnd.
Coins are now come to for use yet not popular: 200vnd, 500vnd, 1000vnd, 2000vnd and 5000vnd.

US dollar seems to be easy using when traveling inside Vietnam. Chinese money is sometimes accepted. You can exchange money in bank, travel office or even shopping center.
Visa card, master card or travel cheque are accepted in major cities and travel destinations. However, it is best to bring some sort of cash with you on your holiday.