Abstract: A synthetic film which comprises at least two unmixed polymeric components, at least one of the components occurring in the form of substantially endless threads in the longitudinal direction of the film. The threads have transverse dimensions that are smaller than the thickness of the film and are embedded in a basic mass of a different polymeric component.The process for producing such synthetic films includes the steps of arranging at least two polymeric components, in the liquid state, side by side in a particular order to form a single main stream; repeatedly dividing and doubling the main stream into a multi-layer stream; temporarily dividing the multi-layer stream in a direction transverse to the direction of the layers at least once into sub-streams on the order of magnitude of the layer thicknesses in situ, while retaining the continuity of flow of the multi-layer stream and then extruding the resulting stream containing a plurality of the sub-streams through a casting slit to form said film.