Micro-CT (X-ray microtomography) is a non-destructive technique that can provide information of internal structure of materials. It is very attractive in materials science field since the microstructure affects macroscopic properties of a material. This method has great potential when dealing with materials having complex structure, where high variability of characteristics exists. This paper describes an experimental procedure for evaluating structure of knitted fabric, used for reinforcements in polymer composites, at mesoscopic scale. The 3D geometry of the undeformed knitted fabric is determined experimentally using X-ray tomography. Size and orientation of cross-sections for glass and steel knitted fabric and yarn paths are obtained. Described methodology can be applied for determining knitted fabric structures, results can be used for further micromechanical modelling.