Carbon-fibre-reinforced polymer (CFRP) composites derive their excellent mechanical strength, stiffness and electrical conductivity from carbon fibres. The mechanical deformation and electrical resistance are coupled in these fibres that make them inherently sensors. Thus CFRPs can be considered as a self-monitoring material without any need for additional sensing elements. However, for this to become reality the conductivity map of the entire structure needs to be constructed and the relationships between the conductivity and various use-and damage-related variables need to be established. Experimental results demonstrate that internal damage, such as fibre fracture and delamination, decreases the conductivity of composite laminates. In general, the information about the damage size and position can be obtained by utilising electrical impedance tomography (EIT)..