The UTMB World Series is an annual international ultra-trail circuit, featuring 26 races in 16 countries. It caters to long-distance trail runners, not road runners, with race categories from 20K up to 100-mile ultras.
The series was established by the Ultra-Trail du Mont-Blanc group, succeeding the former Ultra-Trail World Tour. Runners progress through Qualifiers, Events, Majors, and Finals. Finishers earn Running Stones at Events and Majors. The top male and female runners can secure direct entry into the Finals, which includes the Ultra-Trail du Mont Blanc.