The determination of the three-dimensional structure of proteins is key to understand their biological function and malfunction in disease. A modern method for the determination of such structures is X-ray crystallography (complemented by nuclear magnetic resonance and cryo-EM). In order to determine a three-dimensional crystal structure of a given protein, large single crystals have to be grown. After passing this initial bottleneck other labour-intensive steps follow. These include crystal optimization, data collection at synchrotron sources, data processing as well as structure determination and interpretation of the structural data. The X-ray crystallography facility of the Ulm university (XtalFacility Ulm) as a central research- and service unit is meant to make this comprehensive method available to scientists at the Ulm university and for external users in a collaboration- or service-like approach. The facility is run by the Institute of Pharmaceutical Biotechnology.