Most international visitors are required to obtain a Ugandan visa prior to arrival, which can be done online. Around thirty countries, mostly in Africa and the Caribbean (as well as Ireland and Singapore) are exempt, and instead, receive a free visa on arrival. For nationals of other countries, including the U.S., a single-entry tourist visa costs $50 and is valid for six months. All visitors must have a valid yellow fever vaccination certificate in order to receive a visa or enter the country.