Trail du Josas is a spring trail-running event held annually in Jouy-en-Josas, Yvelines, Île-de-France, approximately 20 kilometers from Paris. Taking place between late March and early April, it features adult trail races of 15, 25, and 35 kilometers, alongside children’s races of 1, 1.5, and 3 kilometers. The longest route involves a climb of about 700 meters, indicating it is more than a simple forest run near the capital.
The courses traverse the Bièvre Valley, with paths crossing waterways, passing local heritage sites, and varying in trail surfaces and gradients. Established in 2009, the event attracts trail runners from the Paris region, while also accommodating children and families. Post-race amenities include medical support, aid stations, osteopath massages for participants, award ceremonies, and a communal meal for runners and their families.