Reverse osmosis (RO) has been established as a reliable process for seawater desalination. The reliability of the RO technique depends upon the extent of the pretreatment that must be designed to reduce the suspended and colloidal materials in the feedwater, During the last 15 years of research and development work at the Doha Research Plant (DRP), the Kuwait Institute for Scientific Research (KISR) has evaluated various types of pretreatment technologies for RO systems. These included: conventional pretreatment (CP), microfiltration (MF) and the beachwell (BW) intake systems. This paper gives brief description of these pretreatment technologies which were implemented at DRP and discusses their performances.