An optical module of a headlight for a motor vehicle, for giving a cut-off beam and comprising a plurality of reflectors, including a reflector which is situated below the horizontal plane that passes through the optical axis and that defines a meridian curve which consists of an elliptical arc; a curve situated in front of the end of the elliptical arc, the front end of this curve being coincident with the second focus of the elliptical arc, or close to the focus; and together with a lens surrounds at least one zone of the lower portion of the convergent lens, or, in the absence of any convergent lens, surrounding the zone through which the rays pass in the plane of the lens.