The mechanical properties of stereoblock polypropylene/isotactic polypropylene blends have been analyzed at different temperatures and at large deformations. The samples at a lower content of isotactic polypropylene show good elastic properties, both in terms of deformation reversibility and in terms of energy dissipation in the hysteresis cycles. Considering the dependence of the elastic behavior on the temperature, the model that can be suggested is based on the presence of a physical network in which the cross-linking is due to cocrystallization between the matrix (the stereoblock polypropylene) and the crystalline domains of isotactic polypropylene.