42km Legendary event

coureurs sur l'aiguille des posettes
Logo 42km du Mont-Blanc

Mont-Blanc 42km

The weekend's flagship race, stage 2 of the Salomon Golden Trail World Series.

Logo Golden Trail World Series powered by Salomon

It brings together the very best in the discipline to 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 at ease on all types of terrain and are self-sufficient for several hours. We draw your attention to the fact that a runner without an UTMB performance index above 350 points has very little chance of finishing the race, so it is more advisable to take part in another Mont Blanc Marathon event.

See the list of those selected for the draw

Race course

Semi-autonomous TRAIL. Open to 'Espoir' category and above

6 starting waves

2,300 runners maximum

Maximum time: 10 hours

3 full feed stations

1 finish refreshment station

View interactive map

Download PDF map

Départ 42km 2023
Coureurs sur un sentier avec un mont enneigé en arrière plan
Arrivée Rémi Bonnet 42km 2023

Delivery of race numbers

Number collection at Place du Mont-Blanc by appointment only:

  • Thursday June 27, 2024 by appointment
  • Friday June 28, 2024 by appointment
  • Saturday, June 29, 2024 by appointment

Participants will only be able to pick up their race numbers during the time slot they have chosen. No bibs will be issued to runners outside their time slot. At the 42km race number collection, runners must present their photo ID and race bag, including all compulsory equipment for the timing chip and equipment check. Race numbers will not be issued to runners who fail to present their bags and equipment.

No race numbers will be issued on Sunday morning before the start of the race.

Compulsory equipment

  • Cell phone.
  • Minimum 0.50-liter water supply.
  • Waterproof jacket with hood (gore-tex type) adapted to your size.
  • Whistle.
  • Survival blanket.
  • Tumbler

Recommended equipment depending on weather conditions

  • Cap.
  • Tights.
  • Gloves.
  • Roll of straps.
  • Bowl and spoon.
  • A little money

SAS start organization

The start of the Mont-Blanc 42km is organized in 4 waves. 

Depending on your airlock, please report to the location shown on the map below.


Plan de départ 42km : organisation des sas de départ


Description of the 42km Mont-Blanc course

After setting off from the Place du Triangle de l'Amitié in Chamonix (1035m), you gradually climb up the Chamonix valley, passing through the hamlets of Les Bois and Le Lavancher to reach Argentière (1250m).

Runners bypass the village of Argentière and reach Le Planet via the Chemin des Rambles, before continuing along the small northern balcony to the village of Le Tour.

From here, the route heads towards the Aiguillette des Posettes (2185m) along a path passing through the Chaleyre.

The route then descends to the village of Vallorcine via the Col des Posettes (1997m) and the Plan de l'Envers path.

From Vallorcine (1260m), you reach the hamlet of Le Buet, then take the Chemin des Diligences to the Col des Montets (1461m) in the heart of the Aiguilles Rouges nature reserve.

Facing the Mont-Blanc chain, the path rises to La Flégère (1875m).

After a balcony traverse to the combe de la Charlanon, you'll finish with a long descent on a lovely path that takes you back to Chamonix to finish the run on the Place du Triangle de l'Amitié.

Time barriers

The time limits indicated below are given for information only, and may be modified if necessary for the safety of participants. 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.

A runner arriving at a time barrier after the deadline will be disqualified. The lower right-hand corner of the race number will be "cut out" by the race marshal, and the runner will be asked to take public transport back to Chamonix. If the runner wishes to continue the race, his or her number will be collected by the station chief and the runner will no longer be considered a participant in the 42km du Mont-Blanc, and will therefore no longer be under the responsibility of the organizer.

Anyone disrespecting the volunteers in charge of this function will be permanently banned from all Mont Blanc Marathon events.

  • Tour feed station (km 14 ): 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): start time for last wave + 8.30 hrs.

In the case of a wave start, time barriers are calculated according to the start time of the last wave.

Revivez les éditions passées du 42km du Mont-Blanc