Abstract: A photoelectric measurement head (26) for the monitoring of the cross-section of a profiled section between an extruder and a calibrating device of an extrusion press for the manufacture of plastic profiled sections (24) is provided in the region of a free head end of the measurement-head housing (30) with two light-passage openings (38, 42) for a light outlet and light inlet respectively. The light passage openings are arranged on opposite sides of a passage (40) for the profiled section. In each opening (38, 42) a light-transmitting glass cover (64, 66) is inserted. Furthermore, two heating elements (60, 62) are inserted in the measurement-head housing (30) in the region of its free head end in the direct vicinity of the glass covers (64) and (66). The heating elements are connected to a temperature-setting device which maintains the temperature of the free head end of the measurement-head housing at the temperature of the profiled section (24) at the nozzle outlet of the extruder.