Membrane filtration has become firmly established as a primary technology in ensuring the purity, safety and efficacy of modern Biopharmaceuticals. As the Biopharm/Biotech industry comes to maturity filtration has a key role to play in the reliable and economic production of a wide range of biologically active products. This paper will review the application of membranes from microporous, through ultrafiltration to nanofiltration/reverse osmosis types using actual examples of systems designed for cell harvesting, protein concentration, small molecule processing, virus removal and sterile filtration. In order to meet the challenges of the industry these systems must be state of the art and the paper will review the detailed design of such systems highlighting such aspects as integrity testing, product recovery, clean in place, steam in place and system control and optimization. The talk will give detailed downstream process sequences for several biological products, e.g. monoclonals, vaccines, and small molecules, showing the sequence of separations from fermentor to final product. Details of each major unit operation, cell harvest, ultrafiltration, virus and sterile finishing will be presented - with technical details and actual process examples and pictures of equipment installed in European Biotech companies, together with some points on how to improve operation, productivity and yield.