Visas are required for all foreign visitors to Laos. A fifteen-day visa on arrival can be bought for $30 (US dollars cash only, plus one photo), but is only available to travellers entering Laos at Wattay Airport in Vientiane, Louang Phabang Airport or at the Friendship Bridge between Thailand's Nong Khai and Vientiane. If entering Laos from Chiang Khong in Thailand's Chiang Rai province, you can obtain fifteen-day visas through Chiang Khong guesthouses and travel agencies: processing takes 24 hours and costs the baht equivalent of $50. Thirty-day visas can also be arranged here for much the same price but take three to four days to process .

If you want to enter Laos via somewhere other than these border points, or if you want a longer visa, you will have to apply for an advance visa at a Lao embassy or a tour agency. Many visitors opt to do this while staying in Bangkok or Hanoi. In Bangkok , you can obtain thirty-day visas directly from the embassy for B750-1050, depending on nationality, plus an additional B300 "fax" charge; fifteen-day visas cost the same. You need one passport photo, and processing takes two days (or 12 hours for an extra B300). An alternative option is to go through one of the travel agents in Bangkok's Khao San area, who charge B1200-2000 for a fifteen-day visa, and twice as much for a thirty-day visa; allow three working days for processing. The Lao consulate in Khon Kaen in northeast Thailand can also issue visas, though fees and processing times are variable.

Travellers from Vietnam can get visas for Laos at the Lao embassy in Hanoi or at the consulate in Da Nang . The embassy in Hanoi charges $25-35 for thirty-day visas, depending on nationality. In Da Nang , a thirty-day visa costs around $50 and takes two days; for an extra $13 you can get it on the spot. A seven-day transit visa costs $30 (two days), but you must exit to Thailand from Savannakhet. The Lao Embassy in Hanoi does one-month "visit visas" ($50-70; seven days). Transit visas ($25-40; four days), are only valid for five days and for one province (so not an option if you're travelling via Cau Treo). The one-day express service costs an extra $20.

Transit visas , good for only ten days and non-extendable ($25-30; allow three working days), are offered at the Lao embassy in Hanoi for travellers to Bangkok who wish to make a short stopover in Vientiane, and are also offered by the consulate in Kunming, China.

In Vientiane, you can apply for visa extensions at the immigration office on Hatsady Road. Most travellers are charged $3 per day, but you could pay as little as $1 per day; similarly, the length of your visa extension is up to the official on duty. Officially, only the immigration office in Vientiane can issue visa extensions, but it's always worth trying in other towns. Both airport and border immigration offices generally charge $5 per day for overstays.