The national currency in Bahrain is the Dinar, with each dinar devided into 1,000 fils. Notes appear in denominations of BD20, 10, 5, and 1, and 500 fils. Coins are in denominations of 200, 100, 50, 25 and 10 fils.
The dinar has been officially pegged to the US dollar at the rate of $1 = BD0.378. The reverse conversion works out to BD1 = $2.65.
Currency can be changed at the airport, hotels, banks and exchange houses. Rates at the exchange houses are generally better than you might get at the airport or at hotels. There are no restrictions on currency movement in or out of the country.