Abstract: The present invention relates to an orthopaedic lumbo-sacral corset obtained by the assembly of semi-rigid elements and of an inflatable pad. The orthopaedic lumbo-sacral corset according to the invention is made of two side half-shells of a semi-rigid plastic material, connected along the adjacent dorsal edges by a semi-rigid thin band forming a hinge adapted to be generally aligned with the spine of the wearer so as more clearly to orient the shells, with attachment and tightening structure between the adjacent front edges of the two half-shells and an inflatable lumbar pad forming two symmetrical pads relative to the axis. This orthopaedic lumbo-sacral corset is usable for the treatment of chronical lumbar diseases and difficult sciaticas.