| UCI Mountain Bike World Championships | |
|---|---|
 Moments before the start of the under-23 men's cross-country race at the 2009 World Championships in Canberra, Australia. Eventual winner Burry Stander is second from left. | |
| Status | active |
| Genre | sports event |
| Date(s) | varying |
| Frequency | annual |
| Inaugurated | 1990 |
| Organised by | UCI |
The UCI Mountain Bike World Championships are the world championship events for mountain bike racing in the disciplines of cross country, downhill, and four-cross. They are organized by the Union Cycliste Internationale (UCI), the governing body of world cycling.
The first three finishers in each discipline at the World Championships are awarded gold, silver, and bronze medals. The winner of each discipline is also entitled to wear the rainbow jersey in events of the same discipline until the following year's World Championships. Unlike other UCI-sanctioned mountain-bike races, the competitors in the World Championships represent national rather than commercial teams. The World Championships are usually held towards the end of the season.