Abstract: A top for sealing an elongated tube such as a test tube, a blood drawing tube or the like has a tubular body with a closed upper end, a depending sidewall and an opened lower end which form an open ended tube receiving chamber. The lower end of the sidewall tapers outwardly and forms an enlarged entrance. An annular sealing rib, which is formed at the upper interior corner of the tubular body, extends inwardly into the tube receiving chamber and sealingly engages the lip of the tube when the top is in place. An annular gripping rib, which is formed in the sidewall below the sealing rib, grippingly and sealingly engages the sidewall of the tube. A lower rib, which is formed below the gripping rib, facilitates placing of the top on the tube and gradual breaking of the seal when the top is removed. A thumb tab at the lower end of the sidewall assists in the removal of the top from the tube.