A sign structure comprises an elongate support member 10 with a cross sectional shape which is substantially constant along its length, and includes weakening means 18 which are arranged to permit removal of part 16 of the support member so that a sign member 26 can be received, in an assembled condition, within the aperture created by the removal of part 16. The sign member 26 may be an estate agents advertising board and the support member 10 may be a post to which the sign member 26 is assembled.