An adjustable connector for optically connecting a pair of optical fibres in end-to-end relation, whereby insertion and tilt losses at the connector are minimized, is disclosed. The basic connector includes a pair of base plates, each of which can receive therein an optical fibre, the fibre terminating at a beam expanding lens held within the base plate. Confronting faces of the base plates abut a separating resilient washer member and a plurality of screws axially pass from one base plate to the other about and adjacent the outer edge thereof. With the fibres locked in place a test signal is passed through the connector along the fibres and the screws are individually rotated to angularly adjust the base plates relative to each other until the received test signal is optimized. The screws remain in the adjusted position and the connector may then be placed on service. Either fibre can be disconnected from and reconnected to its base plate without disturbing the adjustment. Also the lens may be part of the fibre termination or it can be secured in a separate holder if the fibre already has a commercial terminal connector thereon. In the latter case the terminal connector is held in an appropriate adapter which is in turn held in its base plate adjacent its lens.