The paper is focused on the experimental investigations and rheological characterisations in magnetic and electric fields of liquids based on water in crude oils emulsions, added with ferrofluids (two types of crude oils are used in experiments: asphaltic and paraffinic, respectively). The final samples disclose weakly effects in the presence of magnetic field (saturated magnetization: M-n < 300 [G]) and behave almost as isolators in electric field (conductivity: sigma < 10(-5) [S/m]). The main goal of the Study is to explore to what extent rheometry of complex fluids in electric and magnetic fields is able to offer value information about the internal structure of the samples. The experimental results prove that anomalous rheological behaviour (thixotropy, non-monotonic flow curve or viscosity function) of a complex fluid (in our case, emulsions based on paraffinic oil) generate also thixotropic properties and non-monotonic answers in the presence ferrofluids, under low magnetic and/or electric fields intensity. Our prospective study suggests that novel experimental procedures based on interaction: electro-magnetic field-complex fluids can be developed, in order to determine indirectly some relevant rheological properties of the complex fluids with internal network structure. (c) 2008 Elsevier B.V. All rights reserved.