Melt-spun isotactic polypropylene (iPP) fibres have been prepared with moduli of about 12 GPa and strength of 730 MPa. Single-fibre model composites are prepared by embedding constrained high-modulus iPP fibres in thin films of a matrix material based on the same isotactic polypropylene grade. The morphology of these composites has been investigated by optical microscopy and low-voltage scanning electron microscopy techniques. After isothermal crystallisation from the melt a transcrystalline layer was found having lamellar crystals grown perpendicular to the fibre axis. The work illustrates that the processing of polypropylene fibre reinforced polypropylene composites as self-reinforced single-polymer composite systems is feasible and that these composites may fulfil the demands for fully recyclable engineering composites. (C) 2001 Elsevier Science Ltd. Ail rights reserved.