The enzyme 3-dehydroquinase catalyzes the interconversion of 3-dehydroquinate and 3-dehydroshikimate. The enzymes are classified into two groups, type I and type II, which have different biochemical and biophysical properties and act with different mechanisms. The type II dehydroquinase of Helicobacter pylori, a dodecameric enzyme, was overexpressed in Escherichia coli. The recombinant protein has been crystallized at 296 K using polyethylene glycol (PEG) 4000 as a precipitant. Native X-ray diffraction data have been collected to 2.5 A resolution using synchrotron radiation. The crystals are cubic and belong to the space group P4(2)32, with unit-cell parameters a = b = c = 98.91 A. The asymmetric unit contains one subunit of recombinant type II dehydroquinase, with a corresponding V(M) of 2.18 A(3) Da(-1) and a solvent content of 43.6%.