The Peruvian New Sol is the current currency. US Dollars can be used in most restaurants (at a poorer exchange rate). UK pounds and Euros are not recommended.
Current exchange rates:
1GBP = 4.23 soles and 1US$ = 3.25 Soles (correct as of July 2017)
All large towns and airports have ATM’s that accept Credit (Visa preferred) & normal bank cards (Connect, Cirrus).
Banks will accept paper credit card withdrawals – but the hours and queues are annoyingly unsociable.
Money changing houses are available in all towns. US Dollars are the preferred currency; GB Sterling is not widely accepted.
Out of towns try to have as many small coins and notes as possible as change is not widely available.