The variation of the mechanical stiffness during fatigue loading has been shown to be an important qualitative and quantitative damage analogue. A correlation between stiffness reduction and the development of the various types of damage, such as intra- and interply cracking, delamination growth or fibre fracture, has been made by various authors. In this paper, the in situ detection of the temperature increase during fatigue loading together with the measurement of the variation of the electrical resistivity is reportecl. Both tech-niques promise to be valuable analogues to monitor damage development