An extracellular alpha-galactosidase was isolated from fungus Trichoderma reesei. The purified enzyme had a molecular weight of 54,000 Da and an isoelectric point of 5.25. Crystals of alpha-galactosidase were obtained from a polyethylene glycol 4000 solution by the hanging-drop method. Seeding was used for enlargement of the crystal size. The crystals belong to the orthorhombic space group P2(1)2(1)2 with cell dimensions a = 122.2 A, b = 81.0 A c = 49.7 A and diffract beyond 3.0 A resolution.