This paper deals with new fouling resistant RO membranes which are made more hydrophilic and less charged or charged with the same charge as the foulants to reduce hydrophobic interaction and charge attraction or to increase charge repulsion, respectively. The fouling resistant membranes were recently manufactured by Saehan Industries, Inc. in Korea via coating RO membranes with hydrophilic monomers followed by polymerization and cross-linking reaction. The fouling resistant RO membranes showed much less flux reduction than the regular RO membrane when both membranes were subjected to 30 ppm dry milk, 50 ppm a cationic surfactant, 50 ppm a nonionic surfactant and 50 ppm humic acid, respectively. The coated membranes were characterized in terms of membrane surface charge (zeta potential) and hydrophobicity (contact angle). The coated membranes showed much less negative charge than the regular uncoated membrane, but the contact angle of the coated membrane was about the same as the regular membrane. The membrane surface charge was controlled using various coating compounds. The membranes with various surface charges were dyed with a cationic dye such as methylene blue. The intensity of dyeing was linearly correlated with the degree of the negative charge on the membranes. The regular uncoated membrane was dyed the most since it has the most negative charge. The membrane fouling by the cationic surfactant was also linearly correlated with the degree of the negative charge on the membranes. The membrane fouling by the nonionic surfactant and humic acid had some relation with hydrophobic interaction between the foulants and the membranes. The membrane fouling by the dry milk appeared to be influenced by a mixture of hydrophobic effect, charge effect and some colloidal deposits. In a field test using 8040 elements, the fouling resistant membrane maintained much higher permeability than the regular membrane when both are fed with an industry wastewater at Hyundai Motor Co. for about 40 days. The fouling resistant RO membrane has been successfully in operation for treating wastewater at Samsung Electronics Co. for about five months. Includes 5 references, tables, figures.