The Gim complex (GimC) from Saccharomyces cerevisiae is a heterohexameric protein complex, also known as prefoldin (PFD), which binds and stabilizes unfolded target polypeptides and subsequently delivers them to chaperonins for completion of folding. In this study, the crystallization and preliminary X-ray analysis of one of the beta subunits of the Gim complex (Yke2) from S. cerevisiae are described. The purified protein was crystallized by the vapour-diffusion method, producing two types of crystals that belonged to the orthorhombic space group C222 or the primitive monoclinic space group P2(1). The unit-cell parameters for the C-centred orthorhombic crystal were a = 48.2, b = 168.86, c = 131.81 A and the unit-cell parameters for the primitive monoclinic crystal were a = 47.83, b = 134.90, c = 81.50 A, beta = 100.71 degrees . The Yke2 crystals diffracted to 4.2 and 3.1 A resolution, respectively, on a rotating-anode generator under cryoconditions. This is the first report concerning the crystallization of a beta subunit of a eukaryotic prefoldin.