The semi-interpenetrating networks gels of hydrophobically-modified poly(acrylic acid-acrylamidemethacrylate) and amylose were prepared using 4,4 '-bis(methacryloylamino) azobenzene as a crosslinker. Investigation of mechanical strength of gels showed that the equilibrium elastic modulus G changed from 12.4 to 32.9 g/cm(2) with increasing the contents of amylose in the case of low content of crosslinker. The swelling behavior of gels indicated that the aggregation of the hydrophobic groups of hydrogels could be destroyed by expanded amylose and the electrostatic repulsion between the charged -COO- groups because of the ionization of the carboxylic groups in pH 7.4 buffer solutions. The hydrophobicity and flexibility of the side chain, the entanglement extent of the amylose, and the ionization of carboxyl groups in the gels greatly affected the swelling rates and swelling ratios. Investigations of swelling/deswelling periodically in pH 2.2 and 7.4 media indicated that the semi-IPN gel was more pH-sensitive than the nonsemi-IPN gel.