Abstract: A disposable blood sampling device wherein inner and outer spaced apart pad members, separated by a compressible pad-bridging enclosure respectively carry an axially extending evacuated collecting container closed by a penetrable end cap and an axially aligned, double-ended cannula. In normal position the cannula is maintained in withdrawn position within the enclosure. The cannula is prevented from penetrating the cap of the collecting tube when the outer member is depressed toward the inner member until after penetration of the epidermis has occurred.