Sulfotransferase STF1 from the Mycobacterium tuberculosis H37Rv genome was overproduced in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. The crystals diffract to 1.5 A resolution using synchrotron radiation at SPring-8. The crystals are monoclinic and belong to space group P2(1), with unit-cell parameters a = 40.86, b = 95.76, c = 48.04 A, beta = 106.43 degrees. The calculated Matthews coefficient is approximately 2.1 A3 Da(-1) assuming the presence of one molecule of STF1 in the asymmetric unit. A substrate-binding assay using a PAP-agarose column suggests that STF1 exhibits sulfotransferase activity.