A door access control and key management system is disclosed, in which a number of doors and door users are involved. The system comprises a door/key administering system and a door lock/control assembly mounted on each door, which are communicatively interconnected with each other via a communications network. The door/key administering system serves to store a key unique to each of the users, store an identification code unique to each of the doors, and assign access authorization to at least one user for each door. The door lock/control assembly serves to read the key presented by the user, verify that the key has access authorization, and operate the door in response to the authorization for access. Each user can gain access to the doors authorized to the user with a unique key and each door can provide access to the user or users assigned thereto.