The mode I interlaminar toughness and intralaminar fracture toughness, and mode II interlaminar shear fracture toughness of a thermoplastic and a toughened thermosetting polymer reinforced with aligned and cross-ply carbon fibres are investigated over a wide range of temperature. The nature of the fracture process and fracture resistance are explained qualitatively on the basis of measurements of toughness, crack-tip and crack-wake events, and post-mortem fractographic analysis. (C) 1997 Elsevier Science Limited.