In the stretch/blow molding process of poly(ethylene terephthalate) (PET) bottles, various parameters such as displacement of the stretch rod, inflation pressure, and polymer temperature distribution, have to be adjusted in order to improve the process. An axisymmetric numerical simulation code has been developed using a volumic approach. The numerical model is based on an updated-Lagrangian finite element method together with a penalty treatment of mass conservation. An automatic remeshing technique has been used. In addition, a decoupled technique has been developed in order to compute the viscoelastic constitutive equation. Successful stretch/blow molding simulations have been performed and compared to experiments.