The agitation effect on the heterogeneous graft copolymerization of a mixture of vinyl acetate and methyl acrylate onto cellulose was studied. Two procedures for the addition of the reactants were employed. Stirring speed, agitation time, and magnetic as well as mechanic stirring were tested. This polymerization system undergoes significant changes in the reaction parameters under low and high stirring speeds as well as under short agitation times. An explanation of the results is given.