Currency is Euro in French side and Antilles guilder (ANG) in Dutch side (1 Euro=around 2ANG)

But dollar is most used currency in the island.
Attention, Dutch guilder is systematically rejected, even in Dutch side. Traveller’s checks are accepted but rarely metropolis’s checks. Cash and credit card are the best payment ways. You find many cash dispensers in the island. Some allow withdraw Euros and other allow withdraw dollars.