An experimental investigation was aimed at understanding extrusion operating parameters and polymer properties important to the skin surface appearance of extruded EPDM products. The purpose of this study was to develop general guidelines that can be applied to the design of new products in sponge and/or dense profiles for a variety of consumer applications, including automotive weatherstrips. In many of these applications, cure and physical properties as well as extrusion performance in terms of high line rates, low swell, and smooth surface appearance are important. This paper concerns the relationships between the hydrodynamics of extrusion and skin appearance as well as the desirable molecular characteristics for achieving smooth skin surface. The study shows that polymers with broader molecular weight distributions have a significant advantage in processing latitude over those of narrow molecular weight distribution, with skin appearance shown to depend on the extent of viscous heating during the forming operation.