Numerical simulations have been performed of viscoelastic flow in double-layer coextrusion of polymer melts. The constitutive equation used is a realistic integral model of the K-BKZ type, which can describe the viscoelastic memory of polymer melts. In particular, coextrusion of a typical PS/HDPE system through a slit die has been simulated. The model constants have been determined using experimental data available in the literature. The simulation results reveal bending of the extrudate. The occurrence of bending can be justified using the relative values of the rheological properties of the melts. Bending can be eliminated for certain extrusion rate regions while it is dominant in others.