UDP-N-acetylenolpyruvylglucosamine reductase (MurB) is an essential enzyme in the bacterial cell-wall biosynthetic pathway, making it a potential therapeutic target for novel antibiotics. Diffraction-quality crystals of both the native and Se-methionine-expressed MurB from Staphylococcus aureus have been prepared by sitting-drop vapour diffusion from solutions containing polyethylene glycol (PEG) 8000, ammonium sulfate, sodium cacodylate pH 6.5 and dimethyl sulfoxide (DMSO). Crystals belong to the cubic space group I2(1)3, with unit-cell parameters a = b = c = 178.99 A. X-ray data from these crystals were collected at the Advanced Photon Source 17-ID beamline and were used to solve the MurB structure to 2.3 A resolution.