An ankle brace for therapeutic and preventive treatment of ankle sprains including a foot shell having upright medial and lateral sidewalls and a curved posterior wall, medial and lateral upright members hinged to the sidewalls, an anterior band formed integral with and connected to the upper ends of the upright members for positioning across the tibia crest of a wearer, a leg strap connectable around the leg of a wearer and the anterior band for holding the band against the leg of the wearer, a foot strap connectable between the medial or lateral sidewall near the posterior wall at an angle across the top of the foot of the wearer to a forward portion of the opposite sidewall, and an ankle strap connectable from the same medial or lateral sidewall as the foot strap and around the ankle of a wearer above the medial and lateral melleoli of the wearer and around the opposite upright member. In a preferred form the foot shell, upright members, and anterior band are formed of thin molded plastic and the leg, foot strap, and ankle strap are formed of fabric materials.