Abstract: A preferred embodiment of the invention provides an ankle-foot orthosis (1) for resisting plantarflexion of a patient's foot, comprising a resiliently flexible sock-like orthotic structure (1) formed of first (12) and second (14) tubular sections set at an angle to one another, wherein the second tubular section is capable of being opened for insertion of the patient's foot and lower leg into respective ones of said first and second tubular sections, the orthosis further comprising at least one closure member (34) that can be passed round at least part of the periphery of the second tubular section and secured in place to urge the second tubular section towards a closed position in which the second tubular section is closely fitted to the lower leg of the patient.