Hydrogels based on three kinds of polyaspartamides, i.e. non-substituted polyaspartamide, substituted polyaspartamide with sodium aspartate pendant and that with sodium sulfonate pendant, were prepared by crosslinking of polysuccinimide with ehylenediamine, followed by the hydrolysis with the corresponding amines (ammonia, sodium aspartate, and sodium 2-aminoethylsulfonate). Water absorbency and biodegradability of these products were evaluated, comparing with those of crosslinked sodium polyasparate prepared similarly. Absorbency in pure water of the three products in the present study was in the range of 70-150 g/g, somewhat lower than that of crosslinked sodium polyasparate, 200 g/g. Absorbency in 0.9% NaCl solution was totally lower than those in pure water and the order of the absorbency of the products was the same as the case of the pure water. On the other hand, in 3.5% NaCl solution, absorbency of crosslinked polyaspartamide containing sodium sulfonate was higher than that of crosslinked sodium polyasparate. The crosslinked polyaspartamides in the present study showed somewhat slower biodegradation speed than the crosslinked sodium polyasparate.