The first use of dendrimer nanotechnology in the modification of reverse osmosis (RO) membranes is reported. The effects of dendrimer surface coatings on the advancing water contact angle (i.e., coatings' hydrophilicity), permeate flux and % salt rejection of commercial polyamide membranes were studied. The membranes were coated by in situ crosslinking of amine-functional polyamidoamine (PAMAM) dendrimers and PAMAM-polyethylene glycol (PAMAM-PEG) multi-arm stars with difunctional PEG crosslinkers. The resulting coatings significantly reduced contact angles of membrane surfaces without affecting their % salt rejection and only moderately reducing their permeate fluxes. Lower contact angles indicated more hydrophilic membranes with the potential for increased resistance to fouling by hydrophobic foulants, such as biofoulants and organic pollutants. Published by Elsevier B.V.