23km: a historic race
23km du Mont-Blanc
Created in 1979, the Cross du Mont-Blanc will celebrate its 45th edition in 2024.
This friendly race, whose course has remained virtually unchanged since its inception, will take you in the footsteps of the discipline's pioneers, all set against a panorama of dazzling beauty!
To take part in this race, you'll need to have previous mountain running experience, be comfortable on all types of terrain and be self-sufficient for several hours. Please note that a runner with an UTMB performance index of less than 270 points has very little chance of completing the race, so it is recommended that you take part in another Mont Blanc Marathon event.
Before registering, we strongly recommend that you familiarize yourself with the course, profile and estimated time table, so that you are fully aware of the difficulty of this race. The time limits indicated below take into account any slowdowns you may encounter, and we strongly advise you to plan your race with a margin in relation to the time limits.
2025 race route
23km semi-autonomous short trail
1680m+ / 870m-
Open to Espoirs category and above
Limited to 2,000 runners
6 starting waves
Maximum time: 6 hours
2 full feed stations
1 finish refreshment station
Number withdrawal
Pick-up of race numbers for the 23km will be by appointment only, at the Espace EMC2 on Place du Mont-Blanc (Chamonix):
Thursday June 26, 2025 from 9am to 9pm,
Friday June 27, 2025 from 9am to 9pm,
Runners must present photo ID and a race bag containing all compulsory 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 papers. No race numbers will be distributed on the Saturday morning before the start of the race.
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.
Time barriers
The time limits given below are for guidance only. In the event of bad weather conditions, and for safety reasons, the organization reserves the right to stop the event in progress or to 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 station chief and the runner will be invited to return to Chamonix. Should the runner wish to continue on the course, 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; he or she will therefore no longer be under the responsibility of the organizer. Anyone disrespecting the volunteers responsible for enforcing the time limits will be banned from all Mont Blanc Marathon events.
- Montroc feed station (km 12): start time of last wave + 2h30.
- La Flégère feed station (km 18): start time for last wave + 4.30 hrs.
- Maximum race time - Chamonix Planpraz (23km) : Start time for each wave + 6h.
Maximum race time
Runners crossing the finish line after the maximum race time will not be classified and therefore not considered as finishers. This maximum time is calculated according to the start time of your wave.
23km du Mont-Blanc: maximum race time 6h00
Course description
After setting off from the Aire des Parapentes, the course gradually climbs up the Chamonix valley, passing through the hamlets of Les Bois and Le Lavancher to reach Argentière (1250m). Runners bypass Argentière to reach Le Planet via the Chemin des Rambles. They then head for Montroc along the local road, before picking up the footpaths again to reach the hamlet of Tré le Champ, a pretty village just before the Col des Montets, and continuing along the south-facing balcony towards La Flégère. After crossing over to the magnificent Combe de la Charlanon (1812m), the race continues on a lovely balcony trail overlooking the Mont-Blanc Massif, which will take runners all the way to the finish.
The organizers would like to draw runners' attention to the fact that, depending on the systems and settings used, GPX tracks can give very different results (from 1485m to 1981m of positive ascent for the 23km).