Single crystals of UDP-N-acetylglucosamine enolpyruvyltransferase of Enterobacter cloacae have been grown by vapor diffusion using phosphate buffer as the precipitant. The crystals belong to the monoclinic space group C2 with a = 86.9 Angstrom, b = 155.9 Angstrom, c = 83.8 Angstrom, beta = 91.6 degrees. Assuming two monomers per asymmetric unit, the solvent content of these crystals is 63%. Flash-frozen crystals diffract to beyond 2 Angstrom resolution. (C) 1996 Academic Press, Inc.