Transfructosylation of the β-fructofuranosidase I from Arthrobacter sp. K-l was investigated. This enzyme catalyzed both transfructosylation and hydrolytic action, when it was incubated with sucrose alone. But in the presence of a suitable acceptor such as D-xylose and lactose, the enzyme catalyzed mostly transfructosylation and transferred the fructose residue preferentially to the acceptor. The enzyme had broad acceptor specificities. D-Xylose, D-galactose, L-sorbose, D- and L-fucose, D- and L-arabinose, maltose, isomaltose, cellobiose, lactose, meiibiose, xylobiose, maltotriose, methyl β-glucoside, and galactoside were efficient acceptors in the transfructosylation. On the other hand, D-ribose, L-rhamnose, D-mannose, 2-deoxy-D-glucose, D-galactosamine, D-galacturonic acid, and 1-kestose were not efficient acceptors. Various primary alcohols, polyhydric alcohols including some sugar alcohols, and some glycosides acted as acceptors, but secondary alcohols with one hydroxyl group such as 2-propanol and 2-butanol were not effective as acceptors.