2-Keto-3-deoxy-6-phosphogluconate aldolase (KDPG aldolase, E.C. 4.1. 2.14) is a member of the pyruvate/phosphoenolpyruvate aldolase family. It is also a synthetically useful enzyme, capable of catalyzing the stereoselective aldol addition of pyruvate to a range of unnatural electrophilic substrates. The recombinant protein was purified by a two-step HPLC protocol involving anion-exchange and hydrophobic chromatography. Dynamic light-scattering experiments indicated the protein to be monodisperse. Crystals were obtained using the sitting-drop vapour-diffusion method, with PEG 6K as precipitant. Diffraction data were collected on a frozen crystal to a resolution of 2.26 A on station PX9.6 at the Daresbury synchrotron. The crystal belongs to space group P2(1)2(1)2(1), with unit-cell parameters a = 53.2, b = 77.9, c = 146.8 A.