A comprehensive real estate lockbox system is disclosed which provides a variety of operational features. Some of these features include the ability to : record all accesses to all lockboxes; transfer all or part of such records from the lockboxes to a supervising real estate agency or board; organize and review such records; facilitate operation of lockboxes that are mounted in awkward or poorly lit locations; limit lockbox accesses to preselected agents, agencies or boards; reprogram lockboxes in the field; monitor redundantly the status of the lockbox battery; record diagnostic information on each operation of a lockbox or key; render keys inoperative on predetermined dates; disable unauthorized keys; grant agents from remote real estate boards permission to open certain lockboxes, and; grant different keys different privileges.