Structural changes induced by defined shear deformation in conductive polymer composites containing carbon fibres or carbon black are investigated using simultaneous electrical-rheological measurements. This work presents first systematic study concerning the electrical behaviour of composites with anisotropic microfiller under deformation in the molten state. It was found that the electrical conductivity of composites with carbon fibres reacts very sensitively on the mechanical deformation. For instance, at a deformation amplitude of 0.1 the electrical conductivity oscillates over three orders of magnitude. On the other hand, the composites with carbon black display distinctly more stable conductive particle network resulting in only small variations in the conductivity under comparable conditions of deformation. The differences in the electrical and rheological behaviour of the composites are explained by distinctly stronger inter-particle interactions in the case of carbon black. The experiments presented show that conductive polymer composites containing micro-sized anisotropic particles could be a perspective material for deformation sensors or switches. (C) 2018 Elsevier Ltd. All rights reserved.