Human sorbitol dehydrogenase (SDH) was expressed in Escherichia coli BL21 cells and purified using ammonium sulfate precipitation and anion-exchange and dye-affinity chromatography. Purified SDH was crystallized from polyethylene glycol solutions using the hanging-drop vapour-diffusion method. X-ray data were collected to 2.75 A resolution. The crystals belong to the monoclinic C2 space group, with unit-cell parameters a = 145.9, b = 52.3, c = 169.0 A, beta = 101.8 degrees. This is the first crystallization report of human sorbitol dehydrogenase.