Enzyme use for biofilming control in whitewater circuits has long been in the focus of discussions. This strategy is targeted to partly or completely replace organic microbicides that are currently being used. Since the selection of enzymes or enzyme systems is decisively dependent on the nature of the extracellular polymeric substances (EPS) in a biofilm, these substances had to be analysed in order to identify the principal components ofa biofilm matrix. Developing suitable analytics for the determination of EPS in biofilms was one of the crucial and most time consuming efforts in the context of enzyme use. By gaining in-depth knowledge of the EPS composition in biofilms occurring in PM circuits, researchers have enabled enzyme products to be provided for specific circuits. In addition, modern test methods allow biofilming phenomena to be studied in test rigs. These analytical methods and laboratory tests were used to create a number of enzyme formulations which have already been applied in the paper industry. Since April 1995, trials have been conducted on a paper machine for the production of woodfree writing and panting paper in a nepal process. These trials are aimed at reducing both the microbicide dosages and the specific treatment costs. Initially, a microbicide enzyme combination was added into the process. After two months, the microbicide dosage in whitewater 1 was reduced by 60% and after 4 months it was discontinued altogether In a second step, the enzyme dosages were optimized. Future project steps will be devoted to an optimization of the treatment costs. The experiences gained with enzymes for biofim control on a laboratory and mill scale have encouraged the authors to continue their work in this field. However, it seems doubtful whether enzymes are the sole answer to the complex problem of biofilming in PM whitewater circuits. A combined use of microbicides biodispersants and enzymes appears most promising when it comes to developing an environmentally compatible and low-cost method of treatment.