Yeast Cia1p is a homologue of human CIA (CCG1-interacting factor A), which possesses nucleosome-assembly activity and interacts with the human TFIID subunit CCG1 and the C-terminal domain of histone H3. The yeast Cia1p without the C-terminal polyanionic stretch has been expressed in Escherichia coli, purified to homogeneity and crystallized by the hanging-drop vapour-diffusion method using PEG 8000 as precipitant. The protein was crystallized in orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 106.70, b = 46.92, c = 40.60 A and one molecule in the asymmetric unit. The crystal diffracted beyond 2.95 A resolution using synchrotron radiation.