The invention relates to an optoelectronic sensor, in particular to a light grid (10), having at least two circuit boards (19, 19-x) which are to be arranged one after the other in a longitudinal direction (16, z direction) and on which a plurality of light transmitters (18) and/or light receivers (20) are arranged in series, wherein the circuit boards (19-1, 19-2) are fixed in a desired position with respect to one another by a functional element (34) and wherein the circuit boards (19-1, 19-2) are held in a housing (12). It is proposed to provide an improved optoelectronic sensor, in particular a light grid, that the housing (12) is configured as a section and the circuit boards (19-1, 19-2) are held via the functional elements (34) in oppositely disposed grooves (50, 52) of the section (12) which extend in the longitudinal direction (16, z direction) so that the functional elements (34) position the circuit boards (19-1, 19-2) in a fixed position perpendicular (in the x-y plane) to the longitudinal direction (16, z direction).