The present study deals with the production and properties of a fructosyltransferase from Actinomyces viscosus which was found to be an extracellular enzyme. In batch and in continuous cultures, the enzyme activity was low at high exogenous glucose concentration. This relationship may be indirect and result from secondary effects such as the production of inhibitory substances or proteolytic enzymes or, in the case of batch cultures, by retardation of growth. The properties of fructosyltransferase from A. viscosus were similar to those described for fructosyltransferases from other bacterial species.