The met repressor from Escherichia coli has been crystallized in space group P21, with unit cell dimensions a = 35.6 A, b = 62.6 A, c = 44.5 A, beta = 102.4 degrees and one aporepressor dimer per asymmetric unit. Preliminary X-ray diffraction photographs show measurable intensities to beyond 1.5 A resolution, and the crystal form is ideally suited to high-resolution crystallographic analysis (1 A = 0.1 nm).