A novel type of reverse osmosis membrane has been introduced to field operation in 1996, the biofouling resistant (FR) membrane. It is a chemically modified thin film composite, aromatic polyamide membrane in a tailored spiral wound element construction. When these elements are synergistically coupled with the optimized use of a select biocide, the combination FR technology package has demonstrated dramatic reductions in chemical cleaning frequency. In the meanwhile, many plants have been built and are in operation worldwide. At the same time, the product is being further developed. This poster presents some case histories and field experience with the first two generations of FR membrane during the past four years.