All visitors, except citizens of Indonesia, Malaysia, Singapore, Philippines, Laos, Thailand and Vietnam, need a visa to enter Cambodia. The official price for a tourist visa is US$20 and US$25 for an ordinary visa. Staff may try to charge more at some land border crossings, so hold out for the official price, particularly at major crossings, but don’t be upset if you have to pay 1 or 2 dollars extra.
Visas can be obtained at Cambodian embassies or consulates. Visas are also available “on arrival” at international airports, all six international border crossings with Thailand, some international border crossings with Vietnam, and at the main border crossing with Laos.