Phosphoribosylpyrophosphate synthases (PRS; EC 2.7.6.1) are enzymes that are of central importance in several metabolic pathways in all cells. The sugar cane PRS enzyme contains 328 amino acids with a molecular weight of 36.6 kDa and represents the first plant PRS to be crystallized, as well as the first phosphate-independent PRS to be studied in molecular detail. Sugar cane PRS was overexpressed in Escherichia coli, purified and crystallized using the hanging-drop vapour-diffusion method. Using X-ray diffraction experiments it was determined that the crystals belong to the orthorhombic system, with space group P2(1)2(1)2 and unit-cell parameters a = 213.2, b = 152.6, c = 149.3 A. The crystals diffract to a maximum resolution of 3.3 A and a complete data set to 3.5 A resolution was collected and analysed.