Ski7 (superkiller protein 7) plays a critical role in the mRNA surveillance pathway. The C-terminal fragment of Ski7 (residues 520-747) from Saccharomyces cerevisiae was heterologously expressed in Escherichia coli and purified to homogeneity. It was successfully crystallized and preliminary X-ray data were collected to 2.0 Å resolution using synchrotron radiation. The crystal belonged to a trigonal space group, either P3121 or P3221, with unit-cell parameters a = b = 73.5, c = 83.6 Å. The asymmetric unit contains one molecule of the C-terminal fragment of Ski7 with a corresponding crystal volume per protein mass (VM) of 2.61 Å(3) Da(-1) and a solvent content of 52.8% by volume. The merging R factor is 6.6%. Structure determination by MAD phasing is under way.