Synchrotron small-angle X-ray scattering (SAXS) studies were carried out to investigate effects of thickness of injection-moulded isotactic polypropylene (iPP) plates on shear-induced morphology and morphological distribution through the depth direction of the plates. Different levels of effective shear flow are imposed on the iPP melt by changing the thickness of the plates although the injection moulding is performed with the same injection ram speed and the same melt and mould temperatures. Shish-kebab-like morphology is found roughly 100 mum from the surface of plates, regardless of the thickness of plates. However, the type of shish-kebab-like morphology is very sensitive to the thickness. The shish-kebab structure at the surface region can be changed into the kebab-structure only or random crystalline lamellae as the thickness of the plate increases. The preferential orientation of crystalline lamellae along the flow direction strongly depends on the thickness of the plate, although the melt-shear does not significantly enhance the degree of linear crystallinity. It is also found that in the core region, the slow relaxation of polymer chains in the thick plate results in a higher degree of linear crystallinity. The results indicate that the shear-induced morphology is strongly dependent on effective shear flow and should be described individually. (C) 2004 Elsevier Ltd. All rights reserved.