The protein complex crystallographic beamline BL19U1 at the Shanghai Synchrotron Radiation Facility is one of the five beamlines dedicated to protein sciences operated by National Facility for Protein Science (Shang-hai, China). The beamline, which features a small-gap in-vacuum undulator, has been officially open to users since March 2015. This beamline delivers X-ray in the energy range 7–15 keV. With its high fiux, low divergence beam and a large active area detector, BL19U1 is designed for proteins with large molecular weight and large crystallo-graphic unit cell dimensions. Good performance and stable operation of the beamline have allowed the number of Protein Data Bank (PDB) depositions and the number of articles published based on data collected at this beamline to increase steadily. To date, over 300 research groups have collected data at the beamline. More than 600 PDB entries have been deposited at the PDB (www.pdb.org). More than 300 papers have been published that include data collected at the beamline, including 21 research articles published in the top-level jouals Cell, Nature, and Science.