Abstract: A reflector for an oblong light source is disclosed, which includes a conical part (1) to which a curved part (2) connects. The inside of both the conical part and the curved part of the reflector have longitudinal grooves extending longitudinally along the parts. A number of grooves in the curved reflector part (2) are provided with a reflection face (8) which runs parallel to a line passing through the starting point and the finishing point of the groove bottom (6). The reflection face is oriented to face towards the central axis of the reflector.