An intra-articularly located ligament in the first metatarsophalangeal joint of the left foot has been detected in a patient. The intra-articular ligament was dorsomedially attached to the head of the first metatarsal and to the inferior part of the articular face of the base of the proximal phalanx of the big toe. In a literature search we could not find any report of a ligament located intra-articularly in this particular joint. Such a variation may have a role in the etiology of hallux valgus.