Recombinant constructs encoding the fibrinogen-binding domains of ClfA and ClfB from Staphylococcus aureus have been crystallized. ClfA was crystallized in the orthorhombic space group P212121 with unit-cell parameters a = 39.58, b = 81.39 and c = 112.65 Å. A complete data set was recorded to 2.1 Å resolution and had a V(m) of 2.3 Å3 Da-1 with 46.5% solvent, suggesting one molecule per asymmetric unit. Co-crystals of ClfA with the 17 amino-acid C-terminal peptide of fibrinogen γ-chain diffracted to 2.1 Å resolution and had unit-cell parameters a = 39.11, b = 81.39 and c = 109.51 Å in the space group P212121. ClfB was crystallized in the tetragonal space group P41212 or P43212 with unit-cell parameters a = 96.31, b = 96.31 and c = 84.13 Å and diffracted to 2.45 Å resolution. The estimated V(m) of 2.6 Å3 Da-1 with 53% solvent indicated one molecule in the asymmetric unit.