Although it was previously a part of the British West Indies, since 1983 St. Kitts and Nevis has been an independent country, therefore when you arrive or leave you will have to go through customs and immigration. You will need to have a valid passport, but no special visa is needed.

Before you arrive in St. Kitts and Nevis you will be given a customs form to fill in, which will give you the opportunity to declare that you are bringing in certain items that may be liable for duty.

If, while you are on St. Kitts and Nevis, you also visit a neighboring island, be aware that Sint Eustatius is Dutch, Montserrat is British, and Antigua & Barbuda is independent, so you will also need to go through customs and immigration on those islands when arriving and leaving.