A foldable roll-over protection structure is provided for use on a vehicle movable in a generally fore-and-aft direction. The foldable roll-over protection structure includes a frame comprising a base section and an upper section. The base section is connectable to the vehicle. The upper section is swingable relative to the base section between a forward position in which the upper section projects forwardly from the base section, a rearward position in which the upper section projects rearwardly from the base section, and an upright position positioned between the forward and rearward positions. A hinge assembly swingably interconnects the sections of the frame. The hinge assembly is configured to releasably secure the upper section in each of the positions of the upper section.