Abstract: Connection for catheters, perfusion units and flasks containing liquids to be perfused, of the kind used when parenterally administering liquids, principally characterized in that it comprises a chamber containing an antimicrobian product between the components to be connected, that is to say, between the outlet of the container containing the liquid to be perfused and the perfusion unit, or between this latter and the entrance to the catheter, a hollow needle which traverses opposed penetrable wall portions of the chamber and the antimicrobian liquid therein.