An extracellular multifunctional beta-xylosidase was purified from a culture of the fungus Trichoderma reesei. The active 95 +/- 5 kDa enzyme has been crystallized from sodium acetate buffer using PEG as a precipitant. The crystals belong to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 67.75, b = 98.54, c = 227.25 A, and diffract beyond 2.7 A resolution. X-ray data were collected from frozen crystals on a synchrotron source.