An optical plug-in connection for the connection of polarization-maintaining optical fibers includes a sleeve having a bore therein and a receptacle having a bore therein for supporting the sleeve with the bore of the sleeve aligned with the bore of the receptacle. First and second ferrules are provided having bores supporting ends of optical fibers. A first end of the first ferrule is received in one end of the bore of the sleeve via one end of the bore of the receptacle. A first end of the second ferrule is received in the other end of the bore of the sleeve via the other end of the bore of the receptacle. A locking mechanism is provided for locking the first and second ferrules to the receptacle.