From the beginning when it was realised that electrons - like X-rays - are diffracted by the atoms in crystals it was clear that electron diffraction could - in principle - be used in the same way as X-ray diffraction for the determination of crystal structures. However, with increasing understanding of the electron scattering process, in particular by development of n-beam scattering theory during the 50ies of the past century, it became general knowledge that it could normally not be assumed that the kinematical or single-scattering approximation gives even a rough indication of the diffracted intensities. For this reason nearly all activities in this direction were stopped within a few years from that time on. Whilst X-ray diffraction turned over the years into a powerful quasi-automatic method for structure determination, structure analysis by electron diffraction was not seriously developed further over a period of more than twenty years. So it took until 1976 to perform the first structure determination by direct phasing methods from electron diffraction data of an organic compound and another eight years for the first ab-initio structure determination of a heavy-metal oxide from high-resolution electron microscopy images. Due to the strong interaction of electrons with matter structure determination by electron crystallography is the method of choice to analyse atomic structure of extremely small samples