Ageing studies were performed on a carbon fibre-bismaleimide (CBR320/328) system developed by the CSIRO in Australia, with a fibre volume fraction of 55%. This material has a glass transition temperature of 302degreesC and the effect of ageing at 204 and 250degreesC on the interfacial region was studied. A variety of test techniques were employed to characterise interfacial property changes (mode I delamination, SEM, Raman); chemical changes due to ageing (Raman, FTIR); changes in glass transition temperature (DMTA) and weight loss. The results showed that both interfacial and resin degradation mechanisms differed between the two temperatures. It can, therefore, be concluded that accelerated ageing is not applicable to this system. (C) 2002 Elsevier Science Ltd. All rights reserved.