An analysis has been carried out of the crystalline structure of a blend consisting of amorphous polycarbonate and semicrystalline isotactic polypropylene (PP) crystallized under pressure. Structure investigations were carried out by means of wide-angle X-ray scattering. The amount of particular phases as well as the degree of crystallinity have been analysed. It was found that during pressure crystallization, as well as the monoclinic alpha-modification, the triclinic gamma-form of PP also occurs, which disappears after recrystallization in non-pressure conditions. The crystallinity of PP in the blends is independent of the composition of the polymeric mixture.