FKBP52 is a high-molecular-weight immunophilin belonging to the FKBP (FK506-binding protein) family. FKBP52 is one of several chaperone proteins associated with untransformed steroid receptors in steroid receptor-hsp90 heterocomplexes. Here, the C-terminal domain (amino acids 145-459) has been cloned, overexpressed and purified. Crystals were obtained using the hanging-drop vapour-diffusion technique with ammonium sulfate as precipitant in 0.1 M Tris pH 8.0 solution. Diffraction data to 2.7 A were collected from a selenomethionine-containing crystal belonging to space group C222(1), with unit-cell parameters a = 114.4, b = 143.1, c = 171.2 A, alpha = beta = gamma = 90 degrees. There are three molecules per asymmetric unit.