A finite element (FE) model, that explicitly discretizes a single 3D spherulite is proposed. A spherulite is a two-phase microstructure consisting of amorphous and crystalline regions. Crystalline regions, that grow from a central nucleus in the form of lamellae, have particular lattice orientations. In the FE analyses, 8-chain and crystal viscoplasticity constitutive models are employed. Stress-strain distributions and slip system activities in the spherulite microstructure are studied and found to be in good agreement with the literature. Influences of the crystallinity ratio on the yield stress and the initial Young's modulus are also investigated.