A novel mucoadhesive polymer was prepared by template polymerization of acrylic acid in the presence of sericin for a transmucosal drug-delivery (TMD) system. FTIR results indicated that a polymer complex was formed between poly(acrylic acid) (PAA) and sericin through hydrogen bonding. The glass transition temperatures (T-g's) of sericin and PAA in the PAA/sericin polymer complex were inner-shifted compared with the T-g's of sericin and PAA themselves. This may be due to the increased miscibility of PAA with sericin through hydrogen bonding. The dissolution rate of the PAA/sericin interpolymer complex was dependent on the pH. The mucoadhesive force of the PAA/sericin polymer complex was similar to that of a commercial product, Carbopol 971P NF.