The IAU Trail World Championships are annual trail running World Championships, from 2007 up to 2015 was biennial, held for the first time in Huntsville, United States in 2007 and organised by International Association of Ultrarunners.[1]
The 2021 World Mountain and Trail Running Championships (abbreviated WMTRC 2021), held in Chiang Mai, Thailand, from November 4–6, 2022, combined the World Mountain Running Championships and IAU Trail World Championships.