This invention shows a sterile connection device as made in several embodiments but with a common purpose in which a protector may be pierced, penetrated or opened by pressurized fluid flow by means carried on a influent connector member but with the withdrawal of this means the protector is closed to the passage of unwanted contaminents. The influent connector may be conduit, a syringe or a like member with or without a needle, or a influent connector made as a molding and with or without a needle. The protector, if resilient, may be a secured diaphragm; a duckbill valve, or a slit in a resilient wall of a tubular member removably mountable on an extending tubular end of a effluent connector. The influent connector and the effluent connector are formed of plastic with molding processes providing the desired tolerances. The influent connector has means for conducting fluid to and through a small aperture therein and with this small aperture being in and through a small rigid structure device carried by the influent connector. A protector member of a resilient composition and characterized as having residual bias is adapted to be penetrated at a selected area by this small rigid structure carried by this half. A effluent connector has a fluid pathway and conduit therefrom. This effluent connector is adapted to receive and releasably retain this influent connector device and the protector member and with separation of the halves of the connection device the protector is carried in and remains within the effluent member so as to provide a barrier to unwanted contamination of the discharge conduit. A rigid protector is also shown with a one-way valve construction opened with pressurized fluid.