Australian, British, Canadian, US, and EU citizens do not need visas for a trip to French Guiana as a tourist and providing you have proof of a return ticket, you can stay in the territory for up to three months. You must possess yellow fever vaccination certificate and your passport must be valid for at least three months post-travel. No other shots are required, athough protection against endemic diseases is always ideal.
Health and Safety
French Guiana has very good medical facilities especially in prominent cities like Kourou, Cayenne and St Laurent du Maroni. Still, medical and travel insurance coverage is advisable. There are occurrences of hepatitis B and D, as well as Chagas disease and dengue fever.
The territory is a very safe place to travel, but you should be careful not to lose your documents as there are very few consulates and diplomatic representation. Services are mostly provided by embassies in Paris, which means you will be required to travel to France if you run into any problems with your passport, both expensive and a headache.