Abstract: A circuit board spacer is provided for maintaining two relatively flexible circuit boards overlying one another in a circuit board rack in mechanical isolation from each other. The circuit board spacer comprises a roller formed of a plurality of thin, tough, contiguous, flexible disks on a common axle and a support member for securing the roller to the central portion of one of the circuit boards. When one circuit board is inserted into the circuit board rack containing the other circuit board, the roller rides through the ends of leads or terminal pins protruding from the other circuit board, as the roller disks allow complete penetration of the roller by the leads or pins. As a result, the circuit boards, and any portions thereof, are prevented from contacting one another in such a manner as would cause physical damage to the circuit boards or compromise the electrical circuitry thereon.