A motor vehicle headlight comprises a reflector arranged to be oriented along the horizontal axis of the vehicle, together with a light source situated in the vicinity of the focus of the reflector. It also includes a filter which is able to occupy a withdrawn first position in which it does not interfere with the light beam, and a working second position in which it interferes with at least part of the beam. Means are provided for moving the filter between its working and withdrawn positions. The filter is a diffusing and absorbing filter which does not substantially modify the wavelengths of the emergent light as compared with the incident light, and which is arranged so that, with the filter in the working position, a second type of light beam is produced having a reduced intensity, and, optionally, a modified photometric distribution.