A Cellulose macromonomer, N-(15-methacryloyloxypentadecanoyl)-tri-O-acetyl-beta-cellulosylamine (CTA-C15-MA (2); M-2) with number averaged degree of polymerization (DPn) = 13), was copolymerized with methyl methacrylate (MMA; M-1) to give cellulosic copolymer with CTA side chains, PMMA-g-(CTA-C15) (3-A). An absolute molecular weight determined by multiangle laser light scattering (MALS; M-w,M-LS), degree of polymerization of MMA (X) and CTA-C15-MA (Y) of PMMA-g-(CTA-C15) (3-A) were determined to be M-w,M-LS = 6.30 x 10(4), X = 4.14 x 10(2), and Y = 3.86. Cellulose graft copolymer with cellulose side chains, PMMA-g-(cellulose-Cl 5) (3-H) was successfully obtained after deacetylation of the copolymer 3-A. Thermal analysis of copolymers 3-A and 3-H by means of differential scanning calorimetry (DSC) measurements revealed that a small amount of CTA and cellulose side chains affected thermal properties of the PMMA main chain.