Abstract: A security cabinet with a coin operated key-lock has the entire locking system including the coin box and a tamper detector alarm mounted inside the cabinet door. The lock cylinder of the cabinet key-lock is mounted on the latch mechanism and accessable at the front panel of the door. The lock cylinder can be removed and replaced by use of a master key with the door in a locked condition. The key-lock has a cam for operating the latch bolt and a coin detector, also mounted in the door, includes a detaining lever for blocking movement of the latch bolt unless a valid coin is deposited. The coin box is also mounted in the door. A rear panel of the door can be opened for servicing of the latch mechanism, coin box and the tamper detector.