Neuilly en Trail begins at the Alain Mallon sports complex in Neuilly-en-Thelle, Oise department, Hauts-de-France. This trail-running event focuses on forest loops, minimizing pavement and requiring runners to watch their footing. The primary distances offered are short to middle-range trails, with some editions featuring 9 km, 15 km, and 23 km options, while other information lists 12 km and 23 km circuits alongside a 12 km walk.
The longest route measures just under 23 km with approximately 400 m of elevation gain. The 15 km and 9 km routes also provide sufficient climbs to feel challenging for their lengths. The course follows paths and forest tracks through local woods, including Viville and Dieudonne, with each route designed as a single loop. Participants are expected to be self-sufficient, with refreshments available at the finish line instead of frequent aid stations on the course. Trophies are awarded to the first finishers, all participants receive a gift, and the event contributes to the fight against cancer.