Sainyabuli is a province of Laos, located in the northwest of the country.
The province is located in the northwest of the country, and covers all the area west of the Mekong river. It is bordered by Oudomxai Province to the north, Louangphabang and Vientiane Province to the east, and (from the south clockwise) the Thai provinces Loei, Phitsanulok, Uttaradit, Nan and Phayao. The province is quite mountainous and devoid of vehicle roads expect for one north-south route extending from the provincial capital to the Thai border opposite Thailand's Loie Province. The province is rich in timber and lignite, and is considered the rice basket of norther Laos, since most other northern provinces are too mountainous to grow enough rice. Other important crops include maize, oranges, cotton, peanuts and sesame.