The particle morphology of impact polypropylene was examined experimentally in order to understand how the rubber phase produced in the second step of the polymerisation is distributed inside the growing polymer particles, and how the quantity of rubber produced influences the overall morphology of the final product. It was found that the rubber can pool on the surface of the growing particles, but that this pooling is not uniform. In addition, it was observed that the rubber phase does not flow out of the large pore openings on the surface of the particles. A possible mechanism for the distribution of rubber was proposed.