42km: the mythical race
42 km of Mont Blanc
With 2,540 meters of elevation gain, the 42km Mont-Blanc race is the highlight of the weekend.
It brings together the best trail runners in the sport, who engage in a thrilling battle against each other in a breathtaking setting! First along the fast, rolling trails of the race’s opening section, then up the steep and technical slopes of the Aiguillette des Posettes—the course’s main challenge—before finishing with an incredible panoramic view of the Mont Blanc massif.
To participate in this race, it is recommended that you have significant mountain running experience, be comfortable on all types of terrain, and be self-sufficient for several hours. Please note that a runner with a UTMB performance index below 350 points has very little chance of finishing the race; it is therefore recommended that such runners participate in another event of the Mont-Blanc Marathon.
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 feed stations + 1 finish feed station
PDF map
Estimated passage times
Race profile
Race Bib Pickup
Race bibs for the 42km race will be available by appointment only at the EMC2 space located at Place du Mont-Blanc (Chamonix):
- Thursday, June 25, 2026, from 9 a.m. to 9 p.m.,
- Friday, June 26, 2026, from 9:00 a.m. to 3:00 p.m.,
- Saturday, June 27, 2026, from 10:00 a.m. to 9:00 p.m.
Runners must present a photo ID and their race bag containing all required gear so that a timing chip can be attached and their equipment can be checked.
No race bibs will be issued to runners who do not have their mandatory gear and identification documents.
Mandatory Equipment
- A working cell phone.
- At least 1 liter of water.
- Waterproof jacket with a hood (Gore-Tex type) that fits properly.
- Survival blanket (140 cm x 200 cm).
- Cup.
- Whistle.
- Cash.
Recommended gear
- Beanie.
- Tights.
- Gloves.
- Roll of straps.
- Bowl and spoon.
Time Cuts
The time limits listed below are provided for informational purposes only. In the event of inclement weather, and for safety reasons, the organizers reserve the right to halt the race in progress or to modify the time limits. All decisions will be made by the race jury.
- Tour Aid Station (km 13.5): start time of the last wave + 2h45.
- Vallorcine Aid Station (km 23.5): Start time of the last wave + 5h30.
- La Flégère Aid Station (km 34.2): Start time of the last wave + 8h30.
- Maximum race time – Chamonix finish (km 42): Starttime of each wave + 10:00.
If a runner reaches a time cut-off point after that cut-off has been enforced, they will be disqualified. The lower right corner of their race bib will be “cut off” by the station chief, and the runner will be asked to return to Chamonix. If the runner wishes to continue the course, their race bib will be collected by the checkpoint manager, and the runner will no longer be considered a participant in the 42 km Mont-Blanc Marathon; they will therefore no longer be under the organizer’s responsibility. Anyone who shows disrespect toward volunteers and members of the organizing committee responsible for enforcing time limits will be permanently banned from all Mont-Blanc Marathon events.
Maximum Race Time
Runners who cross the finish line after the maximum race time will not be ranked and will therefore not be considered finishers. This maximum time is calculated based on the start time of your wave.
42km du Mont-Blanc: Maximum race time: 10:00
The organizers would like to remind runners that, depending on the systems and settings used, GPX tracks may yield different results regarding race distances and elevation gain.
