Abstract: A cuff mechanism, for use in an automatic blood pressure measuring system requiring no user adjustments to such mechanism, includes an elongated flexible cuff band with a resilient spring associated therewith of a predetermined width defining an enlarged opening for receiving a user's arm. A reversible motor intermittently drives a drum through a slip clutch adjusted to provide a snug, but not occluding, fit of the band about the various sized arms when the drum winds up the band into its contracted state. The spring is generally mounted throughout the width of the band and extends substantially throughout the length thereof which defines the opening in its contracted state. The band is attached to the drum substantially throughout the width thereof so that the drum will exert a uniform force to circumferentially contract the band snugly about the arm and to maintain same in a steady condition.