Muang Xay, also referred to as Oudomxai or Oudomxay, is a city in Laos and the capital of Oudomxai Province. It shares its name with the province it administers and is sometimes written as Muang Xai.
The city lies in the Oudômxai region of northern Laos. As the provincial capital, it serves as the administrative centre for Oudomxai Province.
Muang Xay is commonly known by the alternative names Oudomxai and Oudomxay, which are used interchangeably with Muang Xay for both the city and the surrounding province.