Ag salt nanoparticles were manufactured at high concentration in water in the presence of a series of copolymers of poly(ethylene glycol) and maleic anhydride (PEG-MA). The Ostwald ripening behaviour was then examined using the PEG chain length of the copolymer as a variable. The ripening rate was observed to be very slow compared to previous literature studies of bare or surfactant stabilised particles in dilute solution. Despite the hindrance to ripening caused by the presence of the adsorbed copolymer, the predicted rate was shown to fit closely to Lifshitz-Slyozov-Wagner (LSW) theory. Particle ripening decreased with increasing PEG chain length. The data highlight the important role of stabiliser chain length for the stability and shelf-life of concentrated nanoparticle dispersions.