The UV quantum efficiency of a Scientific Imaging Technologies (SITe, Beaverton, Ore., formerly Tektronix) 1024 pixel by 1024 pixel thinned and backside-illuminated charge-coupled device has been measured in the wavelength band from 1164 to 5200 Å. The 24-µm-pixel device, which does not have an antireflective coating, has an average quantum efficiency of more than 40% in the band from 1164 to 4000 Å and a read noise of 15 e(-)/pixel.