It is quite well known that injection molded parts made of semi-crystalline polymers present the so-called skin-core morphology: the polymer melt close to the cold walls of the mold undergoes high shear stress and rapid cooling rate, resulting in a highly oriented, fibrillar layer near the wall (the “skin”); in the layers closer to the midplane, lower shear allows the formation of a spherulitic structure (the “core”). The quantitative determination of the main features of the morphology distribution are beyond the predictive possibility of current software for the simulation of injection molding. The thickness of the skin layer, the distribution of the dimensions of the spherulites in the core layer, the relative amount of the crystalline phases inside the sample, are the result of several interconnected phenomena to be taken into account: the effect of temperature, pressure and flow on relaxation time, on nucleation density and rate, on spherulitic growth rate; the distributions of deformation rate and cooling time during the process. In this work, a model for the prediction of morphology distribution in injection molded samples is presented and applied to an isotactic polypropylene, very accurately characterized as far as rheology, quiescent crystallization, effect of flow on nucleation and spherulitic growth rates as well as on the formation of fibrillar structures. The effect of flow on the distribution of spherulite dimensions in the core region and on the thickness of the skin layer is described on the basis of two alternative methods: one based on molecular stretch and the other one based on specific work. The results of simulations are validated through comparison with experimental data collected on molded samples in well characterized conditions. The main features of final morphology are reproduced by the simulations. Keywords: Injection molding, Crystallization kinetics, Flow induced crystallization, Morphology evolution, Isotactic Polypropylene.