Biodegradability of N-acetyl-D-glucosamine (GlcNAc)-substituted poly(vinyl alcohol) (PVA) (1) in a soil suspension (pH 6.5) was investigated at 25 degreesC for 40 days. Biochemical oxygen demand (BOD) of 1 with degree of substitution of 0.2-0.3 (DP = 430-480) was higher than that of PVA under the degradation condition. Size exclusion chromatography (SEC), H-1 NMR, and FT-IR measurements of the recovered sample indicated that biodegradation of PVA main chain was accelerated by partial glycosidation of hydroxyl groups in PVA.