A chitin derivative having monodisperse(1) poly(2-alkyl-2-oxazoline) side chains, i.e., chitin-graft-poly(2-methyl-2-oxazoline) (1), was examined for miscibility with the commodity polymers poly(vinyl chloride) (PVC) and poly(vinyl alcohol) (PVA). The miscibility of the blends was investigated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) measurements. Graft copolymer 1 was compatible with PVC when the content of 1 in the blend was up to 40 wt %. Contact angle measurement against water of PVC/1 blend surfaces indicated that the miscibility of the chitin backbone as well as poly(2-methyl-2-oxazoline) side chains in 1 with PVC was so good that the chitin segment would not migrate to the surfaces of the blends. DSC and FT-IR analyses revealed that graft copolymer 1 was miscible with PVA over the whole composition range.