An access-check system for a network server comprises an access-cache for storing access-permissions generated by the server in response to resource access requests. The system retrieves the appropriate access-permission from the access-cache in response to receipt of a request necessitating the same access-permission as already generated for an earlier processed request. A user-token cache is also employed to assign a unique user-token, to be used in the access-cache, to each user logged on to the server. Changes made to the user-token cache are reflected in the access-cache by removing from the access-cache those entries containing the changed user-token. Changes made to an access control list are reflected in the access-cache by removing from the access-cache those entries containing the server resource with which the changed access control list is associated.