Gallate dioxygenase (DesB) from Sphingobium sp. SYK-6, which belongs to the type II extradiol dioxygenase family, was purified and crystallized using the hanging-drop vapour-diffusion method. Two crystal forms were obtained. The form I crystal belonged to space group C2, with unit-cell parameters a = 136.2, b = 53.6, c = 55.1 angstrom, beta = 112.8 degrees, and diffracted to 1.6 angstrom resolution. The form II crystal belonged to space group P(2)1, with unit-cell parameters a = 56.2, b = 64.7, c = 116.1 angstrom, beta = 95.1 degrees, and diffracted to 1.9 angstrom resolution. A molecular-replacement calculation using LigAB as a search model yielded a satisfactory solution for both crystal forms.