α, β-Poly(N-2-hydroxyethyl-DL-aspartamide), PHEA, one of the poly(amino acid)s having pendent hydroxyl groups, is biodegradable and biocompatible, and has been studied as a useful biomaterial, especially for drug delivery, by appropriate structural modification. In this work, PHEA, which we derived from polysuccinimide, was crosslinked by glutaraldehyde units in the presence of an acid catalyst to provide hydrogels with relatively good gel strength. The dry gels were formed into pressed discs, and their swelling behavior was investigated in different media under various conditions (pH, temperature, etc). In addition, we examined the hydrolytic degradation in aqueous solution. A porous scaffold was fabricated by freeze-drying the water-swollen gel; its morphology was observed by scanning electron microscopy. The PHEA-based hydrogels are potentially useful in biomedical applications; for example, as biodegradable matrices for DDS and tissue engineering.