The national currency is Turk Lira (Turkish Lira). Notes come in amounts in 5,10,20,50,100,200 Lira, coins in 5, 10, 25, 50 kurus (cent). 5 kurus is 0,05 Lira. Traveller’s cheques, Pounds Sterling, US Dollars and Euros are widely accepted in Istanbul. If you have traveller’s cheque and if you want to change it, you will have to go to bank or post office. Exchange offices do not handle them. And you will need to show your passport. 

ATMs: There are ATMs (automated teller machines) where cash may be withdrawn are very common in Istanbul. All ATMs offer instructions in English, German and French. The limit on cash per day is different from bank to bank. All banks have ATM machines. A strip of logos are usually displayed above ATMs to see if they accept international credit cards, bank cards or not. They mostly do. 

Credit Card: Visa, Mastercard and Eurocard are the most widely accepted but you can also use your American express or Dinners card but Amex and Dinner’s aren’t as widely accepted as the others. These types of credit cards are widely used in restaurants, hotels, car rentals, pharmacies, super markets, cafes, shopping centres, boutiques, entertainment venues etc. But basic eateries such as lokanta, pideci, kebapci, borekci ((simple little restaurants mostly for locals), and local markets usually accept cash only. 

Changing money: Banks usually close during lunch time but exchange offices tend to stay open and they may offer a better deal for currency. In the arrivals hall of Ataturk Airport there are 24 hour exchange centres and all other change offices in the city also open between 9am and 7pm. Especially USD and Euros easily changed at exchange offices.