42km: the mythical race
Mont-Blanc 42km
With its 2540m vertical drop, the 42km du Mont-Blanc is the highlight of the weekend.
It brings together the best trailers in the discipline, who wage a breathless battle in a dream setting! First on the fast, rolling trails of the first part of the race, then on the steep, technical slopes of the aiguillette des Posettes, the main difficulty of the course, to finish facing the incredible panorama of the Mont Blanc range.
To take part in this race, it is recommended that you have good mountain running experience, are comfortable on all types of terrain and are self-sufficient for several hours. Please note that a runner with an UTMB performance index of less than 350 points has very little chance of completing the race, so it is recommended that you take part in another Mont Blanc Marathon event.
Race info
42km semi-autonomous trail
2540m D+/-
Open to "Espoirs" category and above
Limited to 2,300 runners
6 starting waves
Maximum time: 10 hours
3 full refreshment points + 1 finish refreshment point 1 finish feed
PDF map
Estimated passage times
Race profile
Number withdrawal
Pick-up of 42km race numbers will be by appointment only, at the EMC2 space on Place du Mont-Blanc (Chamonix):
- Thursday June 25, 2026 from 9am to 9pm,
- Friday June 26, 2026 from 9am to 9pm,
- Saturday June 27, 2026 from 9am to 9pm.
Runners must present photo identification and their race bag, including all mandatory equipment, to enable a timing chip to be fitted and equipment to be checked.
No bibs will be issued to runners without their compulsory equipment and identity documents.
Compulsory equipment
- Cell phone in working order.
- Minimum 0.50-liter water supply.
- Waterproof jacket with hood (gore-tex type) adapted to your size.
- Survival blanket (140cm x 200cm).
- Tumbler.
- Whistle.
- Cash.
Recommended equipment
- Cap.
- Tights.
- Gloves.
- Roll of straps.
- Bowl and spoon.
Time barriers
The time limits given below are for guidance only. In the event of adverse weather conditions, and for safety reasons, the organization reserves the right to stop the event in progress or modify the time limits. All decisions will be taken by the race jury.
- Tour feed station (km 13.5): start time of last wave + 2h45.
- Vallorcine feed station (km 23.5): start time for last wave + 5.30 hrs.
- La Flégère feed station (km 34.2): start time for last wave + 8.30 hrs.
- Maximum race time - Chamonix finish (km42) : Start time for each wave + 10:00.
A runner arriving at a time barrier after the time barrier has been applied will be disqualified. The lower right-hand corner of the race number will be "cut out" by the station manager and the runner will be asked to return to Chamonix. Should the runner wish to continue on the course, his or her number will be collected by the post supervisor and the runner will no longer be considered a participant in the 42km du Mont-Blanc; he or she will therefore no longer be under the responsibility of the organizer. Anyone disrespecting the volunteers and members of the organization responsible for enforcing the time limits will be permanently banned from all Mont Blanc Marathon events.
Maximum race time
Runners crossing the finish line after the maximum race time will not be classified and will not be considered as finishers. This maximum time is calculated according to the start time of your wave.
42km du Mont-Blanc: maximum race time: 10:00 a.m.
The organizers would like to draw runners' attention to the fact that, depending on the systems and settings used, GPX tracks may give different results for race distances and gradients.
