The legal currency unit in the Dominican Republic is the Dominican Peso (DOP).
When you arrive to the Dominican Republic you must buy dominican peso. For that you can go to an Exchange house, or go to a bank and open an account. Avoid exchanging currency from individuals or places that aren’t trustworthy.
Depending on where you come from to the Dominican Republic, your money will have different value.
You can use this link to determine how many Dominican Peso you can receive according to the currency you currently have: (See currency exchange tool)
Remember that these values can change everyday. You can see the current Exchange rate from US Dollars through the Central Bank of the Dominican Republic: (Click here to see the USD exchange rate)