Here are some results on the 3D high resolution characterisation of crystalline microstructures. The technique is based on automated serial sectioning using a focused ion beam (FIB) and characterisation of the sections by orientation microscopy based on electron backscatter diffraction (EBSD) in a combined FIB-scanning electron microscope (SEM). On our system, consisting of a Zeiss Crossbeam FIB-SEM and a TSL/EDAX EBSD system the technique currently reaches a spatial resolution of 100 x 100 x 100 nm³ as a standard but a resolution of 50 x 50 x 50 nm³ seems to be a realistic optimum. The maximum observable volume is in the order of 50 x 50 x 50 µm³. The technique shows all the powerful features of 2-dimensional EBSD-based orientation microscopy and extends them into the third dimension of space. This allows new parameters about the microstructure to be obtained, for example the full crystallographic characterisation of all kinds of interfaces, including the morphology and the crystallographic indices of the interface planes.