A TAXI-type endoxylanase inhibitor from T. aestivum L. wheat flour has been crystallized using the hanging-drop vapour-diffusion method. The needle-like crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 49.92, b = 66.45, c = 106.42 A. From these crystals, a native data set and a gold-derivative data set were collected to 2.25 and 1.75 A resolution, respectively. The heavy-atom derivative of this crystal form was obtained by the soaking method and allowed determination of the initial phases.