A device for masking automobile vehicle headlights comprises at least one transparent optical element (B) inserted on the path of light rays between lighting sources and the headlight glass, the optical element (B) comprising a cylindrical entry face (E₃) with radius R and a cylindrical exit face (E₄) with radius R symmetrical to the entry face (E₃) about a vertical median plane located at a distance 2R from the entry face (E₃) and the exit face (E₄), a mask (C) being placed in the vertical median plane and offset from the horizontal plane of symmetry.