Rubber compounds have high viscoelastic property. One of the viscoelastic behaviors shown in profile extrusion is a extrudate swell. The shape of extrudate is not the same as the die shape because of a die swell. Die Swell of rubber compounds in the capillary rheometry and Labo plasto mill has been investigated through experiment and computer simulation in this study. Simplified viscoelastic model was applied in the computer simulation using commercial CFD code, Polyflow. The Simulation results have been compared with experimental data. The procedure to predict die swell in Labo plasto mill is as in the following. Firstly, weighting coefficients in the simplified viscoelastic model for rubber compounds were determined using capillary die. The weighting coefficients were various for L/D of the capillary die. Secondly, weighting coefficient for extrusion die in Labo plasto mill was claculated using equivalent L/D of the lab extrusion die. Thirdly, viscoelastic simulation using simplified viscoelastic model was performed in the lab extrusion die, and die swell was predicted. Die Swells predicted showed good agreement with experimental results.