Abstract: A method which improves check fraud prevention systems both in printing and verifying checks at their entry points. The method operates by printing on each issued check, a line of encrypted machine-only readable symbols such as a bar-code that contains all the information printed on the check, using a special, key-selectable encryption algorithm. When a check is presented to a bank teller or a cashier, a required, modified reader/decoder device connected to a computer, will read the line of encrypted data and identify a fraudulent check for rejection. The method requires primarily computer software additions and changes. Expensive replacement of existing equipment is avoided.