A display structure is disclosed comprising rectangular panels each having at its upper edge a cross member (7) providing an upwardly open channel (80) which receives a central formation (68) of a retaining member (54) which provides, at its upper end, on opposite sides, respective downwardly open channels (60). In a lowered position of the retaining member, the outer wall (62) of each channel (60) extends on the outer side of the member (7) and can serve to retain the upper edge of a respective display card fitted in the panel. The releasing member can be raised, then tilted, while being held captive on the member (7) by an enlarged lower end part (76, 78) of the central formation which cannot pass between flanges (82) on member (7), to a position to one side of the respective side face of member (7) to allow vertical insertion or removal of the display card or the like. The central formation (68) may also provide an upwardly open channel (72) to receive a downwardly extending tongue on a similar panel, whereby similar panels may be fitted one on top of the other. The panels may have catch members (20, 100) for engagement in cutouts (112) in such tongues to hold together panels thus fitted one on top of the other.