The influence of reagent concentration on monomer conversion and grafting efficiency was investigated for the graft initiated by ammonium peroxidisulfate polymerization of methyl acrylate and natural oil onto starch. The monomer conversion and grafting efficiency increased when the initiator concentration increased. An increase of the monomer concentration led to increase in the monomer conversion and a decrease in the grafting efficiency. The grafting efficiency of oils decreased in the order olive oil, linseed oil, sunflower seed oil. The conversion of natural oil decreased with increase in the oil concentration in the reaction mixtura. The influence of reagent concentration on elongation at break, breaking strength, swelling capacity and water vapor permeability of films obtained from graft copolymer dispersions was investigated. The breaking strength was independent of the concentration of monomers and starch, but decreased when initiator concentration increased. The elongation increased with the increase in the methyl acrylate concentration. The water swelling capacity of films decreased with increase in the concentration of initiator and decrease in the starch concentration. It was independent of the oil concentration.