An ankle-foot orthosis constructed of composite material to assist a person with a foot infirmity in walking comprising an upper arcuate convex shell to engage the anterior of the lower leg and a lower foot support member to engage and support the foot coupled together by an inverted substantially wishbone or Y-shaped intermediate interconnecting member including an upper elongated substantially vertical interconnecting member integrally formed with the upper arcuate convex shell and a lower arcuate convex lateral interconnecting member extending from the lower end portion of the upper elongated substantially vertical interconnecting member to each side of the lower foot support member.