The purpose of this study was to determine if the relative length of the first metatarsal and the proximal phalanx of the hallux, in respect to the total foot length, were associated with the incidence of hallux rigidus. For this retrospective study, lateral radiographs from 132 cases with hallux rigidus and a control group of 132 normal feet were reviewed. We measured the following parameters: the index between the foot length and first metatarsal length, the proximal phalanx of the hallux length, and the sum of the first metatarsal length and the proximal phalanx of the hallux length. We found a statistically significant difference (p: 0.002) between the two groups in the Foot L/1st Mtt L index, and no statistical difference in the Foot L/Phalanx L index. We think that a greater length of first metatarsal is involved in the etiopathogeny of hallux rigidus.