Even though membrane processes are guided by four major driving forces such as temperature, activity, electrical potential, and hydrostatic pressure gradients, this chapter will focus mainly on the use of pressure-driven membrane processes, such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO), in the food industry by referring to both well-established and potential applications. These processes are based on the use of a permselective barrier through which fluids and solutes are selectively transported when a hydrostatic pressure is applied across it. As a result, the feed solution is converted in a permeate containing all the components which have permeated the membrane and a retentate containing all the compounds rejected by the membrane. The first section of this chapter will provide an overview on materials and structures of synthetic membranes. The following section is then focused on membrane design and evaluation of membrane performance. In the last section a summary of established and potential applications of this technology in the food industry will be provided.