The xray diffraction facility, located in 4247 Weiskotten Hall, can be used for crystal screening or diffraction data collection; for macromolecular or small-molecule crystallography. It consists of a high brilliance Oxford Excalibur PX Ultra diffraction instrument with a low-maintenance xray tube, a large Onyx CCD detector (165mm active area) and an Oxford cryo-stream for cryogenic data collection. A 4-circle kappa goniometer allows easy crystal mounting and alignment and permits data collection around any rotation axis. Two stereomicroscopes are available for crystal mounting. Data collection is controlled using the CrysAlis Pro software. The data can be reduced using proprietary routines in the same software, or the diffraction images can be exported in a format compatible with popular data reduction programs such as MOSFLM.