Bacillus circulans E 192 Cyclodextrin-glucosyltransferase was purified 40 fold to homogeneity on a large scale, by affinity chromatogrpahy on a β-CD copolymer cross-linked with epichlorhydrin. A preliminary step was necessary to remove maltooligosaccharides and cyclomaltooligosaccharides from the crude extract. The simplest method consists in performing the affinity chromatography directly from a redissolved 65% saturation ammonium sulfate precipitate of the crude extract. Five successive affinity runs of Cetavlon — treated concentrated extract gave about one gram of pure CGTase with a 70% yield, using 50 g of a 750 U/g β-CD copolymer. This rapid purification is described and the advantages of the method are discussed.