La Transju'Trails takes runners into the Jura Mountains in early June, with steep trail races based in the Haut-Jura around Hauts de Bienne. The schedule ranges from short 5 km and 10 km options to long mountain distances, including 42 km, 62 km, 82 km, and an Ultra 110 km with over 4,000 m of elevation gain. It also features a 15 km hike and youth races, making the weekend suitable for more than just ultra runners.
The longest course runs between Champagnole and Les Rousses, passing Jura water features like the Ain river's "losses" (underground sections) and the Langouette gorges. Other courses still present significant climbing, with 3,600 m on the 82 km and 2,600 m on the 62 km, and bibs are limited for the longer distances. Over 3,000 runners participate in the event, and its name links it to the Transjurassienne, the well-known cross-country ski race held within the same mountain region.