Abstract: Viscosity of solutions of polymethyl (methacrylate)(PMMA) in methyl methacrylate (MMA) at different temperatures and concentrations was investigated by the absolute rate theory proposed by Eyring. The dependences of activation energy for flowing of the polymer solutions on the solution concentration and the molecular weight of the polymer were examined. The dependences of the solution viscosity on the concentration, molecular weight and temperature were approximated by a semi empirical equation. The viscosity calculated from the model agreed well with the value from literature.