A deployable mast structure (100) is disclosed, comprising a body configured to adopt a tubular shape when the mast structure is in a deployed configuration, and a plurality of openings (102) formed in a wall of the body so as to define a plurality of integral tape-spring hinges (103) in the wall of the body, the plurality of openings being configured so as to permit the body to collapse along its longitudinal axis into a stowed configuration when the tape-spring hinges are buckled. In the stowed configuration, the integral tape-spring hinges are configured to exert a force which urges the structure towards the deployed configuration. Since the mast structure collapses along its longitudinal axis, the structure only occupies a small volume in the stowed configuration. A method of fabricating the deployable mast structure from a layered composite material is also disclosed.