The influence of extrusion parameters on the morphology of non-reactive blends has been investigated by means of online light-scattering measurements. A light-scattering device was especially designed to be mounted on a twin screw extruder at different locations along the barrel. The obtained light-scattering patterns were interpreted with respect to the variation of the processing parameters. Preliminary results show that there is little effect of the rotational speed, position along the screw and feed throughput on the morphology but a quite noticeable effect of the blend composition. These results were confirmed by SEM micrographs.