The ruggedly hilly province is sandwished between Phongsali on the north, Luang Prabang on the east, Luang Namtha and Bokeo on the west, and Xayabouri on the south. It also has a short border with China's Yunnan province in the north. As in the other mountainous provinces there are many groups of people living there namely Hmong, Akha, Thai dam Thai khao, Thai Neua, Khamu, Lao Huay, and many others.

Muang Xai, the capital of the province in the northern section, is the junction of the highways connecting the Lao northern provinces: Phongsali, Luang Namtha, Bokeo and Luang Prabang. Better roads are on the northern part of the province, while in the southern part people depend more on the river travel. The lower part of Nam Tha river is in Oudomxai province, where travellers can take boat from Paktha village (where Nam Tha drains into Mekong river) upstream to Luang Namtha taking two days and a night in a village house normally prepared by the boat-man.

Pak Beng on the Mekong river is a famous stop-over place for tourists traveling in slow boats between Luang Prabang and Houixai (border with Thailand's Chiang Khong over the river). It also offers eco- tours to the nearby tribal villages. There are several accommodations available there. The road from Pak Beng to Muang Xai is good in the dry season, and can be passable by tough vehicles in the wet months.